While I like the concept of UH, I think that the reason for using them in ST scenario is situational at best atm, in most movement heavy situations it's better off ignoring them altogether.
I find the idea of Umbral hearts to be very close to the backdraft mechanic of Warlocks from wow (incidentally I think that the ley line teleport is similar to demonic circle) however backdraft also increased the speed of your next 3 casts, so I wonder if they shouldn't make so that UH gives you also the extra speed in addition to the current effect (although that might be OP I'm not sure)
