Ixa'taka currently has an Incarnum-powered killing machine (my Gargel), an Incarnum- and Moon-Magic-fuelled killing machine (Risada's Bandou), and Incarnum- and Druid-Casting-powered killing machine (DaveTheMagicWeasel's character). So a dedicated support caster is welcome.
All the same, we have a lot of bases covered (traps/scouting, sailing, healing, tanking, damage output), so whatever you want works. A party face would be nice, as would a secondary healer. But whatever works.