"So you wish to follow the path of power?"
I'm one of these level 20 characters that you guys have been talking about. Adari is my 20th level necromancer, and if I'm not mistaken the first 20th level wizard in PFS. I'm happy to give some high level advice since not many games get to that point.
Your saves are not high enough- This is how you should view your saves at all times. If there's a way you can increase your saves you should do it. Damage isn't what really threatens to kill you quickly like it does at low levels. Save or die is the bane of high level PCs.
Pull everything you can out of 6 seconds- High levels is where the action economy really comes into play. This applies more to casters than physical fighters, due to the need to full attack. Quickened spells are the bread and butter of high level casters as you now have more spells than you'll likely cast in one day.
It's gonna have resistances- If you rely heavily on a single form a elemental damage you need to have a way to deal, other types of damage. High level creatures will often be resistant or straight out immune to at least one type of energy. This is especially true of high CR outsiders.
It's gonna have DR- As above high CR creatures will often have high damage reduction. I know there's a lot of high damage dealers using a two handed weapon out there, but I've seen several instances where a creature survived a full attack with about 20 hp thanks to it's DR. Then it proceeded to unload on the melee character, and kill her (Sorry Naamah but others need to learn from you, especially those without heroic defiance.). At your level you should be able to afford a magic weapon with a high enough plus to overcome most DR, but you should also spend the extra cash to have an extra weapon of each of the special metals silve, cold iron, and Adamantine.
Carry a backup weapon or 4- At high levels your equipment often makes you who you are. As you gain levels things will go after your precious equipment. Don't be that guy who only carries his signature weapon. Because when you lose it you'll be out of luck.
Kill the guy with the pointy hat or holy symbol- High level spellcasters are bad news. Every turn they get is likely one turn closer to them killing you. If you see a high level caster kill him before he can throw out his big spells.
Have a means of travel- When you get higher levels you'll be expected to find your way to rather out of the way places like forgotten tombs, levels of hell, the moon, ect. Make sure you have a way there, and most importantly BACK.
You can fly?!- At this level you had better have a way to fly in some way shape or form regardless of class. There's nothing worse than getting thrown into a pit of lava and not being able to get out.
Be able to take a hit or three- It doesn't matter if your a wizard or a fighter you need hit points. As much as you might stand in the back at some point you are gonna get hit by something big. Make sure a single hit doesn't knock you out of the fight.
"There's your advice from a venture captain who actually knows what he's doing. Any questions?"
Into the chamber comes a woman with long pitch black hair, a pair of small horns on her head, and the Mark of Lamashtu across her abdomen. A falchion hangs freely from her side, and she looks about as one would a battle field, sizing up everything in the room.
“Greetings Venture-Captain. I am Morgana Arak, Inquisitor of Lady Lamashtu, and for the time being Ruby Sage.” She says with a slight mocking undertone at the thought. “My companions and I have traveled the burning sands and found the fabled Diamond Sage. When she and Amenopheus began to argue over leadership of their order it became quite clear they both would not give in. A vote was called between the sages thought I personally didn’t like either of our choices.”
“Between The Sapphire and Diamond Sage I simply see two beings vying for power in an order of only two. There isn’t enough power to bother fighting over in those sands. Their focus should be in finding the rest of the gems related to the sages before they fight over who should rule. Our decision then was to follow in the ways of Mother Lamashtu. They should gather their power and then compete to see who would be the best leader of their ranks. Once a sufficient number of Sages have been elected there should be a trial made that they all must take part in. Each sage will create a trial, and then each sage will take part in these collective trials. He or she who has been proven the most competent in a test composed of their peers shall be named the head of the order. This system of trials will happen every five years to make sure the head of the order is still worthy of their position. That way the strongest will always rule, and the sages will not sit idly as they have for centuries. If they wish to influence their peers then they have a goal to grow stronger themselves. In this way the order will have a strong leader as well as continually improving members to make sure they can defend themselves from the inside, and out.”
“Now if you don’t mind I have three new children to attend to. Good day Venture-Captain.” She says with a nod and walks out without being dismissed.
83. I will always have a negative boon connected to my plans to make Pathfinders think twice before interrupting my plans.
84. If I am a spellcaster I will always start at least 200ft away from the party at the start of combat even if I don't have long ranged spells.
85. I will always keep one cursed item on my person that I never use in case someone tries to steal from me in combat.
I personally think people are looking way too close to the rules rather than the game it's self. I have a 12th level Necromancer in Pathfinder society who has been making use of spells with the Evil Descriptor his entire career. Never once have I had a GM even talk to me about alignment and the risk of going from Lawful Neutral to Lawful Evil.
Spells in themselves are like weapons. A sword can be used to butcher an innocent on the street or to fend off his attackers. I ask you to think for a minute. Is the sword considered good or evil just because of what it's used for? No the wielder is. Spells cannot in themselves be responsible for what they are used for. It's up to the player to cross the threshold. I myself have used Animate Dead as much as 4 times a session. This is because we had no front-line fighter to soak the damage for our group of casters. Is it evil that I took a dead body and raised it to save my friends from the claws and spells of the monsters we had to face?
Evil spells may be used for good ends. If I summon a devil to walk into a burning building to save someone I wouldn't consider that evil. It's the best creature for the job because it's immune to fire. By the same token good spells may be used for evil acts. A wizard that summons an angel and binds her so he can use her to fight the heroes is an evil act in my view. Tactically it's a smart decision because a Paladin's smite won't work and most hero's don't have the evil aligned weapons to break her DR.
I think labeling as good and evil as a whole is certainly not the way the game was meant to be played. Good, Evil, Law, and Chaos are very real things is Pathfinder but they are all choices as well. An angel may fall just as easily as a demon may find redemption in the right circumstances. It is not unknown for the living embodiment of an alignment to change it's own moral view. In that case nothing should ever be "Always Evil" or "Always Good."
In a final note if this ruling comes to pass drastic changes will have to be made in game. If casting evil spells makes your alignment change then it should be fair that all spells change your alignment no matter what they are used for. Only certain spells like Atonement which was built for dealing with alignment issues have the kind of power to change an alignment just by having it cast. Alignment should be left vague because having an alignment stat would be very pointless. Just my view on the matter.
My most rewarding Mistress
These words shake my cold heart to hear of such politics threatening to displace you from your well deserved throne. Truely this must be a test from Asmodeus himself as all who gain power must be able to maintain it against those who would take it. You however need not worry about falling from his infernal graces for reguardless of what some of these so called "Loyal" servants say you still have devoted supporters amoung us. Just remeber for when this trail is over you have seen the faces of those who would turn on you and those of us who will stand by you in this trial. You have my full support in this matter and I shall lend you whatever you need. Be it spell, voice, ears, or minions. I have made many a tempting creature with my new found powers that I would happily donate to your cause.
Your most loyal collector
Adari The Necromancer