I would slot it into Health/Fast Healing so I can maximize the +HP bonus of High Pain Tolerance.
Adding Healing SOs/IOs to the same power as the Numina's proc is in boosts its effectiveness.
Rising to the Challenge: Spines/Willpower
High Pain Tolerance is a passive anyway. But always slot self-benefitting procs in passives when possible.
Actually, which power you slot it in won't matter so much as whether you also slot additional health enhancements in the power - both of the +regen unique's are not affected by the power in which they are slotted but they ARE affected by the enhancements slotted in that power - so if you have the numina unique plus 3 SO/IO healing enhancements (roughly 95% with ED) you will get a 38% regen boost from the unique instead of the normal 20%, regardless of whether it is slotted in HPT, health or fast healing.
Provided you can spare the slots I WOULD put it in HPT - along with 3 other healing enhancments to max the HP from HPT and the regen from the unique (unless you are into slotting HPT with resistance enhancments as well - but that is rarely worth it). The only reason I would suggest HPT above health/fast healing is that this is the best one to slot up first out of the 3 so this will maximize the benefit of the slots.
Globals: @Midnight Mystique/@Magik13
Fast healing. 3 numina. 1 regen tissue. If you need it there is room for miricle unique and another heal IO as well
I would 5-6 slot RttC with Regenerative Tissue, Numi, and a mixture of healing/endurance enhancements (Or just 3-4 healing IOs if you don't care for bonuses)
@Mojo-
Proud Member of Fusion Force.
slot it in HPT so you have it no matter how low you exemp.
The more people I meet, the more I'm beginning to root for the zombies.
Is this IO better slotted in a toggle like High Pain Tolerance or in a power like Health.