Dealing With A Mounted Character.

I'm about to start DMing a group with these character creation guidelines: 25 point buy (because I want MAD characters to do as good, and we made it a mission on this game to not focus as much on optimization).
Stats can be maximum 16 before racial mods (though I made an exception for the character I will be discussing).
I am giving everyone 150 gp unless they're a fighter, in which I give them 175 gp for average.

Now, to the point. One of my players is choosing to play a gnome fighter (dragoon). This is the first mounted character I've dealt with (although I don't have too much DM experience to begin with, and as a side note it's actually the first gnome too). I would like to know how to deal with this fighter effectively. I don't want to have to commonly find ways to make his mount useless because then that defeats the point of him having a mount. I am excited by the idea of this guy's character and I want him to have as much fun as possible.

http://www.dndsheets.net/view.php?id=30176

He will be best when charging so anything that limits charges puts him on hold.
When he gets spirited charge he will bring the pain especially if he has a lance, but once again the charging is key at least until he finds out about dragon style, and can ignore certain things. He however most likely won't be a spotlight hog, but he will be effective.

What might be some ways I can lessen the amount of charges without outright putting enemies across chasms or putting them high in the air?

What might be some ways I can lessen the amount of charges without outright putting enemies across chasms or putting them high in the air?

a narrow hallway or sneaky ambushers work well, with friendly players in the way that limits his options as well so a mob with decent grapple using his party as anti charging shields.

I would not lessen the charges*. He still won't be doing anymore damage than another character doing full round attacks.

*Well I would sometimes, but most of the time I would not. If you don't get to use a feature there is no real reason to have it.

To answer your question:difficult terrain might work. fog spells. Put minions(low hit point monsters) there to act like road blocks. Even though he can kill them they can stop him, from making a bee line to more important bad guys.

When I said lessen the charges, that is exactly what I meant, only sometimes. As I said, I would like for everyone in the party to be able to make use of their abilities.

So difficult terrain, fog spells, having some minions to block him, narrow hallways, and even finding ways to keep his friends in front of him all seem to be effective. Now, just in case it changes anything, I do not know exactly what the party will end up being yet, but one player has expressed interest in playing a ninja, another a druid (likely taking the domain for better casting, but I am not sure), and the third player doesn't know yet.

If he goes gnome the mount will be medium most likely. That makes the narrow hallway hard to work, but the other ideas should work also. Trying to dismount him might work also. :)

What would be an effective way of dismounting him? His mounted AC is 20 since he can use a shield with a lance that way. His flat-footed AC while mounted is 18, so that's still not easy to hit.
Another thing that is probably important to mention is that his only weapon is a lance, so he can't fight too well up close. He has reasons in his back story as to why he uses the lance only for the most part.

Dismounting his with enemies that have reach weapons is a good option. Difficult terrain hampers him from charging though the thing is that will stop his main damage dealer though the fact is he is still getting a bonus to hitting the enemies on the ground since he is mounted. So even if you disrupt his charge you haven't invalidated with class concept.

If you want to make him wary of charging you can use large creatures or creatures with bracing weapons. Throwing those in every now and again would be fun.

In order to get bonus for being mounted the mount must give him higher ground. If he chooses a medium sized mount such as a wolf he probably won't get the bonus. If he chooses a large mount it makes mounted combat hard if the fights are inside instead of outside.

His mount is medium, so unless the enemies are small, he would not get the bonus to hit for higher ground, correct?
The only thing is, most enemies that parties fight at level one are going to be small things so far that I understand (goblins, kobolds, etc.)
Since his only weapon is a reach weapon, wouldn't be at a disadvantage for enemies to swarm him up close?

I had thought of the bracing weapons, and will definitely be using them to effect at some point. Large enemies will also come, no doubt about that. ;D

That is correct the bonus only applies against small enemies. The enemies could try to swarm him and pull him off of his mount, or at least avoid the lance.

Not having a backup weapon is going to hurt him. I designed a similar character recently so this also allows me to see potential pitfalls if I ever get to play it.

It is good that I am seeing all of this, as one of the things I am trying to do with this group is keep them aware of the major things that will be their weaknesses. Even I won't be able to give them all of the info though, nor should I, they should figure out everything on their own.

And I'm glad to be of help Wraithstrike, even if indirectly.

From what I've read here, it doesn't sound like he is completely doomed if your monsters get in close. Aside from the mount's attacks, remember that proficiency with martial weapons enables a character to make bash attacks with a shield. Whether or not this guy is the sort to remember that or sacrifice his shield AC to beat on some goblins, I don't know but, it's an option (albeit a low-damage option.) Besides that, he can always opt to let his mount attack and then 5-ft-step into an open square to poke the enemy with his lance unless he's surrounded an all sides.

Grappling and Dragging would be pretty effective if you really want him off his mount. He'll take a penalty for not having both hands free if he tries to resist the grapple and doesn't loose his shield and lance. Also, don't forget to let your monsters use Aid Another if you figure they're smart enough to do so.

I'm going to advise that you almost NEVER try to ruin his charges through the use of difficult terrain. The fact is 3E charging rules are totally nonfunctional and we all collectively agree as players that they shouldn't be played the way their written so that anyone can charge ever. The moment you break that pact you're in for a world of hurt, cause he (the player) will basically totally legally be able to call shenanigans on any charge ever made thereafter.

By means of example; Has your character ever charged while in hilly terrain? In mountainous terrain? Over an unworked floor (like a cave perhaps), while in the middle of a forest? Well that's illegal unless you were on a highway! Quick everyone count up how many highways you've ever fought on in DnD as opposed to how many caves.

So yeah. Keep the collective lie going and don't stop someone from being able to charge because their is "underbrush" around and that's supposed to halve movement. That's a road no one wants to go down.

Make a caster and use the create pit spell underneath the horse.

Grappling and Dragging would be pretty effective if you really want him off his mount. He'll take a penalty for not having both hands free if he tries to resist the grapple and doesn't loose his shield and lance. Also, don't forget to let your monsters use Aid Another if you figure they're smart enough to do so.

Wait, so the monsters grapple his mount to get him off or they grapple him while he's mounted? I get kind of confused considering whether or not the creatures are small or medium?

Try to stick with solutions that let your player play his character effectively. Otherwise you'll make him regret his decision to play the gnome dragoon and then fun goes right out the window. You could always just add a few mounted opponent's, like goblins on dog's and kobalds on... bigger kobalds. Mounted humanoids and npc's can easily give your player something to chew on at any level without having to force him to work around some creative handicap.

Hmm, I didn't even think about mounted enemies.
Who would have thought other mounted things would be a nice fight for a mounted PC? xD
Very good suggestions. Again, what I am asking for is things I can do to just challenge the dragoon, not make it impossible for him to have fun. I will have to look at things the same way for everyone else in the party as well, but I have never been a DM for a party with a mounted character nor even played in a party with a mounted character so I wanted to get some advice.

Wait, so the monsters grapple his mount to get him off or they grapple him while he's mounted? I get kind of confused considering whether or not the creatures are small or medium?

Whatever is easier, really. Provided they can reach him, creatures that successfully grapple the rider could attempt to move him to the ground with a second grapple check. Alternately, creatures that manage to grapple the mount can attempt to pin it to the ground the following round and then go for the rider.

Here's an example:

On round one, two goblins and an orc decide they want to pull the dragoon from his mount.

Goblin 1 tries to wrestle the mount, hoping his buddies will be able to grab the gnome. He makes his CMB against the mount's CMD. If he succeeds, he can try to pin it the following round, making it that much easier to catch the gnome.

Goblin 2 wants to go right for the gnome, hoping he can pull the gnome off in the next round. He makes his CMB roll against the gnome's CMD. If he succeeds, he can try to move the gnome off the mount in the following round with a +5 bonus (assuming the gnome fails to free himself.)

The Orc doesn't have time to screw around. He wants the gnome off the mount right now so he uses the Drag maneuver and rolls CMB vs the gnome's CMD. If he succeeds, he grabs the gnome and jerks him to the ground as he takes a step back.

If all of these plans fail, the goblins and their orc friend can use Aid Another next round to gang up on the gnome or the mount, whichever is more convenient.

Keep in mind, the gnome isn't defenseless here. It's unlikely standard goblins and orcs are going to have Improved Grapple or Improved Drag so he and his mount get attacks of opportunity. Additionally, if the mount is grappled, the gnome can use Aid Another, giving the mount +2 to get free. You might also give the gnome a +2 Circumstance bonus to break free of a grapple if his mount is able to twist and turn while the gnome digs his feet into his stirrups or clings to its neck.

Whatever you decide, follow the advice a lot of people have already given you and don't use these tactics in every fight. Every now and then, as a challenge, it can be fun but not every encounter needs to humble the players or point out their flaws. In fact, throw a few encounters at them that specifically point out their strengths once in awhile.

Again, what I am asking for is things I can do to just challenge the dragoon, not make it impossible for him to have fun. I will have to look at things the same way for everyone else in the party as well, but I have never been a DM for a party with a mounted character nor even played in a party with a mounted character so I wanted to get some advice.

Honestly there's a good chance the challenge for the Dragoon is already there without you having to do anything different. If it were me I wouldn't change a thing until I saw how things are going to play out a few times, you know, the wait and see approach. I've played the mounted character before, and things don't always work out like you would expect. Just like any class there are optimal situations where you can really shine and then there are times your lucky to just have participated. He's going to have to mount up for combat if he's not already on his trusty steed when the baddies attack and then maneuver around the party and any terrain to get his charges in properly. I don't know how many rounds your combat encounters usually take but wasting any of them on mounting up and/or positioning kinda sucks. Then there are always the dice. There are always dropped or broken weapons and whiffed attacks. You might only have one or two opportunities for a perfectly positioned charge in an encounter, unfortunately the dice just don’t care. Don't forget his ride checks he has to make occasionally either. No matter how high his skill the dice are going to put the screws to him at some-point.