League of Legends (LoL) Question: Athenes viability on mages that don't heal

Short answer: NO

No item is cost efficient on any champion if it can't use its passive at all. Athene's is already borderline useless on mages*, the only exceptions being those who can use its passive in some way (I think Orianna might use it).

*mages does not include enchanters (i.e. AP supports)

well if you look at aquadragons guy on ap kog maw he recommends buying a chalice of harmony very early but not building it into anything until later. then again the guys a freaking genius. his builds seem wonky but he mathematically tests each and every item. its impressive