This is probably the first ability poll. Still, we have Serene Grace, which encourages secondary effects from moves, and we also have Invigorate, a new ability, which negates secondary effects, but enhances power in return.

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(26/10/10)
Alright, now the full effects of Invigorate/Brute Force is known.

Serene Grace
Effect: Grants a move that has a secondary effect a doubled chance of it happening (so Thunderbolt's paralysis chance is upped to 20% and Rock Smash is now 100%).
Distribution: Blissey line, Togekiss line, Dunsparce, Jirachi, Shaymin-S, Shikijika line (the deer), Meloetta

Invigorate / Brute Force
Effect: Increases the power of a move with a secondary effect by 30%, but that secondary effect (ones that Serene Grace would benefit) wouldn't happen. If Life Orb is the held item, the power increase of those moves stacks, and the recoil from Life Orb is negated (meaning powerful drawback-free attacks).
Distribution: Nidoqueen (only), Nidoking (only), Kingler line, Tauros, Feraligatr line, Steelix (only), Hariyama line, Mawile, Trapinch (only), Bagon (only), Roobushin line, Hihidaruma, Crimgan, Wargle line, Landlos

So, what will it be? Effect or Power?