Besides obviously using it for escaping being downed...
For large groups, if I am within range of them I'll switch into Death Shroud (DS) to cast Life Transfer (LT), then pop right back out of it to save the remaining DS for escaping later or to take down something specific--if I am a little ways off from the group, I'll first zoom into them via Dark Pact.
I also like using LT on destructible environment items like weapon wracks, if one positions themselves correctly, they can take out multiple of them--or bring them pretty close to being destroyed. I also like using DT if there is a really heavy hitting boss--just for variety--to get 'into' the fight a little more.
I am really interested in testing it out fully with the trait system, to see how long exactly one will be able to gain Life Force, stay in the form, how long it takes to recharge, etc. If one can be a pretty close constant DS tank, would be fun to run around from time to time.