For summoner... I'm guessing you get every summon you can and level them up, and get some attack skills here and there for yourself.
Like lasher, which buffs your summons, and your teammates, and hurts monsters for a crappy amount of damage.
Or the witches' skill, magic missile.
It has really fast casting speed can be spammed, and can do really good damage, and it as a good range.
By the way, summoners aren't all that good at pvp, and they're not all that liked in dungeons because the summons lag others sometimes.
In pvp, if you don't have time to summon, you're screwed.
that and if the other person is smart enough to know how to dodge the summons and go straight at you.