How would you go about beating an army of 100 Wyvern. Assume you are level 13 you have a wizards, a cleric, 2 fighter one of which is specialized with the bow and the other with polarms and a ranger.
Cast Greater Teleport, then go somewhere pleasant and have a nice quiet drink.
Unless my math is wrong (possible) this is the equivalent of a CR 42 encounter.
Use your martials as a bait then, when the wyverns attack them cast stuff like cloud kill on their position.
Or what aboniks said.
Would it help if we have a budget of 8,000 gp to use for consumables for the fight? Also we need to protect a kingdom from them. We likely can spend a few days on the project.
Dam Wyvern's having 7 HD so Cloud kill only does a bit of con damage.
Control Winds if your Cleric has either Air or Weather Domain or someone has the UMD to use a druid scroll or two. Then lots and lots of Chain Lightning and/or Call Lightning.
Does the kingdom have an army (or at least some spare casters) you can borrow?
My current thinking is that spells can only do so much damage. Even if I prepared all blast spell and blast scrolls I still have a max amount of damage.
However the Ranger and fighters in my group can likely kill between 3-4 Wyvern's a round when they remain in range. If I cast greater invisibility on all of them that is 13 rounds that makes 39-52 dead Wyverns then we retreat rest up and do it again. Any other spells I should cast and do Wyvern's have some way of fighting though invisibility.
My current thinking is that spells can only do so much damage. Even if I prepared all blast spell and blast scrolls I still have a max amount of damage.
However the Ranger and fighters in my group can likely kill between 3-4 Wyvern's a round when they remain in range. If I cast greater invisibility on all of them that is 13 rounds that makes 39-52 dead Wyverns then we retreat rest up and do it again. Any other spells I should cast and do Wyvern's have some way of fighting though invisibility.
Wyverns have the Scent ability. So they can pinpoint your square even if invisible. After that, you're basically fighting with total concealment (50% miss chance). They may also be able to see where your arrows are coming from -- not sure of the ruling on that one.
Also, is there any reason they won't just fly past you guys and proceed to destroy the kingdom you're protecting?
The more I think about the situation as presented, the less sense it makes.
Wyverns are supposed to be territorial. Like fight-to-the-death territorial. An army of them is bizarre.
Who/what is leading this army?
I wouldn't back yourselves into a cave, I think. Unless the wyverns in question are suffering from some sort of brain damage or a compulsion, a 12 Wisdom is more than sufficient to let them realize that lining up to be murdered one by one is a poor survival strategy. Plus, after you kill the first one and the cave is blocked by the corpse, the other 99 can go attack the kingdom.
Yes it does not make sense, but I heard that in Kingmaker at some point around level 13 there is an attack by a army of Wyverns. I don't know the details of why there is such an attack or how anyone could ever get an army of Wyverns together. Expect for alot of dominate monster of I'm guessing it's aboleths.
You can always blame anything on aboleths.
Ah. Well, easy answer then. Kill the Aboleth. They wyverns will bugger off on their own.
Also:
Well I don't know where these hypothetical Aboleths might be. But that does make me think of another idea cast Magic Circle against Evil on someone who then flys though the wyverns some of them should make their saves to resist the domination. Then cast more Magic Circle against Evil on other wyverns.
See spoiler above (or not, as you choose). The situation is not what you think it is, however.
Still does not answer the question of how an army of wyverns got together.
Still does not answer the question of how an army of wyverns got together.
Raise an army of your own.
Alternatively, prepare (or create scrolls of) at least a dozen summon monster VII and 20 invisibilities.
Have the wizard and clerics invisibly go to the outskirts of the army.
Summon 4 vrock, turn them invisible. Have them fly to the center of the camp.
Turn on music, have them do a little dance for 4 rounds... boom, 20d6 electricity (dance of ruin). If any Vrocks survive, have them go invisible again.
Rinse, repeat.
... or just raise an army.