I’ve personally found great effectiveness using cloud of daggers maybe more than any other spell. Funnelling enemies through a passageway with multiple cloud of daggers cast on the spot is probably my current meta. Then I utilize thunder wave/ black hole to keep the enemies on the other side of the daggers once they make it through.
Another thing if found amazing success with is getting a party to strength 20 as fast as I can, which then I find 90% of enemies can be thrown off cliffs for instant kills. Throwing enemies off cliffs also only requires stealth checks where the body hits the ground and dies.
Lastly there is a fun little cheese strategy I’ve picked up that I don’t see anyone talking about. If you cancel an improvised weapon attack with an NPC before you deal damage, you can move NPC’s without angering anyone.
I cheesed a major boss fight in Act 3 with Thunder Wave. Still got the loot, too, because the baddie was supposed to “escape” after being reduced to 0HP and got put back on the map.