so do the auras last briefly even after they end?
stacking auras is big on similar "state" or "stance" characters in MOBA games, given that they have mana restrictions, and spamming auras to keep all of them active will rapidly leave you useless.
also big is the idea of "activation bonuses," where activating the spell grants an effect (typically offensive in nature), to counterbalance the otherwise team-oriented nature of the class, e.g. damaging and slowing an enemy, damaging multiple nearby enemies, etc.
as good on paper as the idea of a purely supportive class is, the support player still needs to feel like with proper play (kiting, smart terrain use), he can hold his own when things go poorly and his team gets wiped, though obviously, with nowhere near the offensive prowess of an actual fighting class.
not sure how any of that will fit in, assuming the class doesn't have a mana resource or anything of the type (presumably?)
with just the cooldowns/global cooldown, I assume there's no balanced way to stack auras such that the stacking would be useful AND it would be balanced, but I still think the activation bonuses should be at least considered.