As far as snare goes, it would behave normally. If you are asking about a root or another hold, then no they do not break those. The difference being snare only reduces movement speed, where as root or hold immobilizes.
Sentinel tree can be amazing especially if you use sentinel mastery and a aoe stun like thunderclap or tk maelstrom... 2% per target per second healed from any dmg being done, so 5 targets is 10% health per second...this is healing is done partywide on anyone who is damaging the group of mobs you just stunned and is not…
1.) Yes 2.) Yes 3.) It is possible that the power you are using actually drops it below the 15% for the power activation, for example say 15% of your energy would be 15 you have a power that costs 30 and is used when you have enough power to fuel it and it drops you immediately to zero....I have had the most success with…