I'm having a fair amount of success with this force in friendlies at the moment. Typical deploy is 10 sentries and 5 psykers. No regens really seem necessary.
Offensively this is pretty much invunerable to spawn. Mech MTs would be a problem I guess but you can go toe-to-toe against a marine grenadier force on at least even terms.
Defensively your opponent really needs to separate his force so that as they approach you they need to be out of LOS of each other - any unit spotted at end of turn tends to suffer a brain melt as 3-5 psykers saturate him.