Yes, I considered the 3 INT from the set bonus as well.

Magic crits are only +10 MAB originally, but that's not bad either. Also, it can be increased with certain items, such as Goetia Gloves +2 (extra +5 MAB) and Maleficus (+30 MAB). Normally it's not worth it because the chance to get a critical hit is so low, but with some gear that has it in addition to other bonuses, like Nares Cap, Goetia Gloves +2, Maniacus Sash and Hecate's Earring, it actually starts to be decent for average damage, as well as for some interesting spike numbers. It's hard to say how good it would be on regular nukes, though. Meteor's damage is quite simple to plot out.