Sion not double-casting with a mage cap.

My team comp was 4 mage, 4 ocean, 3 shadow and 2 warden.

I've had a HoJ, Frozen Heart and a Mage Cap on my and he'd never proc his mage trait over about 5 games where he managed to get off at least 2 ults.

(Came 2nd because of that in a ranked, but oh well, at least it wasn't 5th)