as it currently stands it is broken skill and needs rework.
in my opinion shadow cloak should be made something like this:
pre morph
- Shadow Cloak - gives player invisibility for 3 seconds, disengages combat, restores players max magicka/stamina/health 2% over 3 seconds(5% at rank IV)
morphs
1) Blood cloak - Shadow cloak +next attack creates blood mist(aoe ranged 5m) affected targets are blinded(30% chance to miss),initial target is concussed (reduces damage done by 10%) and bleeds 2% max Health per second for 3 seconds( 6 seconds at rank IV)
2) Swift Cloak - Shadow cloak + increases stealth/invisible movement speed +50%, incoming damage decreased 20% for 5 seconds(8 at rank IV)
anyhow, game needs more cool skills