Well i really think that the world bosses at least should have more attack types so they are more cool to fight with and for players to be able to use diffrent strategies against them. I like very much what you did with many monsters of the vaults like harpies, and would love to see more special attacks from other monsters and environment.
like:
-giant stone golem thrusting spikes from the ground at some places
-hyenas flanking target while in group
-whirlwind attacks for npcs
-archers charging bow attacks to shoot more distant enemy and using more rapid fire when enemy is close
-new type of arrow: crippling
-more cones (aoe) attacks from enemies - splited by spiders for example
-maybe some environmental objects like statues and trees - comming alive when not expected to attack player
-the traps here and there around in a specific places like a pit with spikes or tree falling when triggered or javelin thrusted from the wall if stepped on the specific floor tile, traps that wouldn’t be very hard to spot but the players (or npcs?) could fall into them eventually and maybe these could even force them to abandon the vault because of corruption or poison etc.
My little thought that i came to right now is that there are many things that can be added to the game that do not include magic at all and that are cool. 