Are you guys kidding? Occ is the new tier 1... early game at least. Late game he becomes way more overpowered than LE was before bite got nerfed.
The effect of Brainstorm is for his level 15 skill and it works, anything else would be even more overpowered than it already is.
Level 15 means 1200 AOE for lighning balls every 5 seconds... in addition to blast off and chain lightning.
Simply spec CL, BOff, BStorm till level 10, then Ball Lightning through level 15 where you go from "obscene" AOE damage to "dear god, what were they thinking" AOE damage.
He HP stacks well, so Blood and Monks early game, Vlemish + Magus Rod + Brain Storm for neverending mana and AOE farming mid-late game, then hit level 15 first and game over.
Thunderdamus predicts in 2 days, you will see the lobby full of "NO OCC!" titled games...