Originally Posted by
Malakh
Depends really. If you don't have that great of a set for Ele as you've been saying, you would be better off with a pure mastery stat-stick, tbh.
Getting that first 'soft-cap' or at least prioritising mastery on the way seems like a good idea. And as haste isn't really one of our better stats in any talent-setup, the Skull isn't that great. If you don't have anything else (or 20 ilvl below the Skull), then use it, the int alone will push you. If you do have other trinkets to choose from with mastery, crit or a great proc (Sentinel's Medallion says hello), then use those - even with 5-15 ilvl lower than Skull they should be better for you.
But when in doubt, sim it.