I think i never lacked plat fairies especially last map of current event have a chance to drop it and i already got 2 from my last 4 runs. Also i was skipping spirit dailies and farm phalanx 2 inst... Well forget it they both drop fairies
If we wouldnt get any breaks like dmm (heard it from u) then plat fairies might be a problem to get. Most events have spirit supplies though... Also i level my troops to 50 then use plat fairies with xp armor. Yeah XP armors are the real problem, at least for me.