User blog comment:Tripleye/mental controller/@comment-155699-20130319190656/@comment-76.107.208.233-20130320202242

Each Level 30 Raid & Alert has a minimum Dominance for Control effects to work on opponents. If you do NOTave the minimum Dominance, you can NOT CONTROL opponents. Tier 4 Raids have a 550 minimum Dominance. I posted the minimum Dominance required for Raids & Alerts a couple weeks ago on this wiki as this question comes up frequently on the official forums.

Dominance over the required minimum does not impact Control effects. So the first stat to focus on in Mods is Dominance just until you hit the Minimum for whatever Tier you are currently in. Newer gear you earn in your Tier will most likely have higher Dominance which will help when you get to the next Tier.

Since Controllers are expected to provide power, Vitalization should be the Mod stat to focus on after you have the minimum Dominance for your Tier.

Finally, you want to use Dual Stat Mods to get the affinity bonus for a slot as this bonus such as Power Critical Chance may not be available as a Mod stat. Dual Stat Mods grant higher overall stats than Single Stat Mods. 2 Dominance & Vitalization Split Mods give higher stats that 1 Dominance Only Mod & 1 Vitalization Only Mod.

My recommendations: Yellow Slots: Dominance & Vitalization Blue Slots: Dominance & Vitalization Red Slots: Precision & Vtalization