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.
Luminous Armor + Callous Glow Ring + any non-darkness inducing AoE is a -10 to -40 on enemy attack rolls. When you consider that +15 is the highest enemy Attack bonus in the game, well, not much is getting through that. This combo on a Light Domain Cleric means you really don’t even need any healing outside of Short Rests.
For Stealth, Silence + Fog Cloud/Darkness is great for maintaining high attitude since no one can see or hear what you are doing. They pair really well in Act 3 for exploring the Lower City.
For Dialog, Keep Enhance Ability on multiple characters (2-3) as this will allow your party face to make all dialog checks at advantage.