Well i started with one and played until level 37 somewhere along mid-Greece in Epic. I changed my skillpoints at this point because i was really bored with the little challenge this build is offering. All you do is heal you pets and hide from enemies. I know theres alot of people who gets the most fun out of the game with the more pet-based builds, and the easy, fast completion of the game, but not me...
There are loads of spells, fun combination skills and challenging builds that let you do the gaming, instead of being passive while automated pets do all the work. But if you like to choose a more passive path in the game, this build is by all the easiest to pick. Maybe the soothsayer spirit/nature is even more easy as you get 1 more pet from spirit mastery.
If you want to play as summoner you have to pick the regrowth line to heal your pets, and heart of the oak is the best skill nature offers as it doubles all hitpoints, both yours and your pets. Wildfire dosen't do enough damage to invest more than 1 point in. Put them into regrowth (1) and Dissemination (10). Else it looks just fine.
This link to how your build should look at level 65:
TitanCalc v0.4 - Summoner - by stonedonkey