A firestarter is basically just a Baby Gilla that's red. He's level 28, I think and you find them after you unlock The Gate of Crius up at the top of the map.
For the record I think WITHOUT Primium (which is how you get Pixie) the PINK LOOMI is the best! I left the game on accedentally and came back 1/2 an hour latter and he had leveled me up 2 times (level 9 to level 11)!
But with primium Pixie is awesome, I mean who wouldn't want a HEALING pet?