clearstream
(He, Him)
And, as DracoSuave hints at, this whole combo, not to mention normal Stealth, isn't even really that powerful.
Hi Buzz. How powerful stealth is depends a lot on how you rule it, and there are conflicting rulings.
Some take the FAQ to mean Stealth = Invisibility. That makes it somewhere near a level 6 daily, only at-will. That seems over the top to me. At the polar extreme, others see it as good for one or no more than two CA opportunities in combat. For both, even for Warlocks, with the investment of 1-2 feats most monsters have little chance of beating stealth.
I have to guess you're running it closer to the latter end, and I certainly agree that many lose sight of the fact it doesn't matter too much what happens inside an action in the vast majority of cases.
-vk