Even as a Monk I forget that I have Invigorate slotted. And your right it is WAY better with much less cost. Why on earth would SE decide this is a good skill to have over a level 22 cross class skill? I would never use 5 chakra to get a measly 300 TP with almost 2 min cooldown. One press on invigorate and i'm good to go for about 6 min of raw DPS. Purify needs another Hook to make me WANT to use it at the cost of 5 chakra like something the name suggests...like an AOE heal or an AOE TP gain. I really hate saying but I don't know what they were thinking when they said monk needs help keeping Grease Lightning up, and something to do when not near a mob. Do you think we are bored?
I personally hate when i'm not near a mob because of an AOE field, and that's fine because AOE is bad and it hurts. But I don't think a WHOLE EXPANSION should revolve around monk having something to do while we wait to get back in there. If that's the case give us a mechanic like WRATH/ABANDON, and give us a skill that resets our Grease timer to 12 secs at the cost of chakra...NOW that I would use. Warrior can poop out wrath like no tomorrow just STANDING STILL and not forced to run around like a psycho spamming one button. THERE IS NO SYNERGY WITH MONK NOW. It's kind of a mess! end rant.