If you slot something like Numina's +Regen/Recovery proc in something that is not a toggle or auto power (like Fast Healing or Health), it will activate when you activate that power, stay active for two minutes, and then expire, only turning on again when you use the power again. This applies to all enhancements that say "for 120 seconds" in the description. If put in a toggle or auto power, these enhancements are instead enabled as long as the power is (thus always with auto powers, or until de-toggled with toggles). Rest is technically a toggle, so I suspect these things would follow the toggle rules in there.
Any proc that does not say "for 120 seconds" will only activate when the power is active, be it toggle or otherwise. Most of these are percentage chance - in that case, in a toggle or auto power, it will check the chance every 10 seconds so long as conditions are met. For a lot of these, the "condition" requires a target (things such as Force Feedback's +Regen, for instance) and will not trigger without one. Others are "non-combat" effects, like Performance Shifter's +Endurance, and can trigger without enemies.
Generally speaking, if the set is an offensive set (damage, knockback, mez effect, etc.), it needs a target. If it is defensive (healing, endurance modification, defence, resistance, etc.), it does not.
Paragon wiki (either paragonwiki.com or wiki.cohtitan.com, same place) is your friends.
http://paragonwiki.com/wiki/Table_of_Special_IOs
There are three types of special IOs, under two sets of rules.
Globals are single IOs that provide a set bonus. These will be self-buffing IOs with no mention of a "chance to X" or a duration.
As long as your combat level is allowed to slot it (so no more lower than IO's level -3) it works, even if the power is unavailable.
Then there are Procs (Chance to X) and 120s (for 120 seconds after...) - both of these work regardless of your combat level, but must be triggered by the power being used. In clicks, it's on the clicks (Attacks, buffs like Fortitude, etc), for toggles it's on activation and every 10 seconds afterwords (attack toggles have some extra rules) until turned off (note, 120s do not work for 120 seconds after turning off a toggle, that is only for clicks), and in auto powers it checks every 10 seconds.
Numina's (and all the regular healing set special IOs) are 120s. So the power must be in use.
Numina's +Regen/+Recovery is a Unqiue as well, as you can only slot one per BUILD. All unique* IOs are Specials, not all specials are uniques.
*All Purple (must be level 50 to slot, set bonuses don't care about combat levels) are marked unique, even the non-special IOs.
Orc&Pie No.53230 There is an orc, and somehow, he got a pie. And you are hungry.
www.repeat-offenders.net
Negaduck: I see you found the crumb. I knew you'd never notice the huge flag.
Thanks to both of you. That clears it up for me.
I have been away from the game for awhile and just recently just started back. I just have some questions on how some of the enhancers work.
Numina's Convalesence +Regen/+Recovery does this have to be in a power that is functioning to work. EI do I have to put it in a toggle for it to active for can I stick it in something like Rest. I know it works in Health but also health technically ticks every x seconds. So was just wondering if I slotted it in a power I never use would it still work.
Also does this apply to all of the Special enhancers. I know the % chance of X effect have to be in a power that activates. toggle/passive/click etc....