Summoning is an old trick for Dungeons & Dragons 3.5 Edition players, and that's no exception to Pathfinder players either. The ability to bring a ton of crazy beasts in, under your control, is undeniably fun.
But what if you could specialize in the ability? What if that's pretty much all you did - and you did it really well? Fear not, this is indeed a possibility - thanks to the Summoner.
Summoners are characters who almost exclusively concentrate their talents on summoning creatures and supporting them in battle. They do this in three ways:
- They have a host of spells that allow them to bolster their summons' stats
- They can use Summon Monster several times a day, not as a spell, but as a spell-like ability that falls outside normal slots
- They can conjure up a personalized Eidolon to fight for them
This last point is probably the most exciting for most players, as the Eidolon is essentially a second character for the Summoner: it's a powerful beast that can, with some tinkering, do dang near anything - including things outside the Summoner's field of expertise.
What those things are depends on the player. When the Summoner is created and goes up levels, his Eidolon gains a number of evolution points that allow it to adopt new abilities. These can include higher stats, improved natural armor for more AC, additional attacks, new limbs, feats and strange abilities that can do a lot of damage in battle. Eidolons can be as varied as a small, human-sized combatant that's little different from a Fighter to a giant worm that can engulf enemies whole.
In order to maximize your Eidolon's abilities, you need to have a general idea of what you want out of the beast. Take a look at the list of evolutions available, then pick out ones which best fit your general picture of the Eidolon. Doing this all at the beginning is much better than haphazardly choosing evolutions as you go along, especially since some don't open up until later levels. You may find yourself regretting your evolution choices if you use them up every level.
There's just one problem with the abilities of the Summoner: the Eidolon can't be used at the same time as the Summon Monster spells. Consequently, you'll have to pick between the two - or take Summon Monster as actual spells - each day. It's often best to save your Summon Monster spells for large brawls and keep the Eidolon out most of the time, though vary your choice based on the circumstances. The Summoner's monsters can stay out a lot longer than usual, so you have a big more wiggle room for deciding.
The Summoner himself is actually of lesser importance to most combats. It is ideal to choose spells that will support your summons while staying out of the fray yourself. Depending on the ruling of your DM, your feats should always include Spell Focus, as that allows you to take Improved Summoning. Other feats should, typically, focus on boosting your Summoner's AC. Skills and equipment vary on the specific build, though all Summoners should concentrate their stat points on Charisma, Dexterity and Constitution.
Summoners are, unfortunately, something of one-trick ponies. Without their summons, they're either completely backup characters or utterly useless. Unless you anticipate that you'll get into a ton of battles, it's best to have another class do your summoning or split your Summoner levels with some other class that's more varied.