It's hammering time!
I figured something out, maybe this is really old news already, but it´s fun.
There´s a hammer in Act 1, that deals AoE damage when you land from a jump. That´s fine, the hammer is unremarkable otherwise.
However. Give it to a monk, and it's a weapon of mass destruction.
See, monks get 'Step of the Wind' bonus actions, that lets you jump for free so long as you have movement speed. And they come with LOTS of movement speed.
So, what you do is; you take your monk. Give him Crushers ring, longstrider etc. You can probably move 20-30m now.
Now haste him. You have double speed now already, so let's say roughly 50m.
But you also have two actions, dash - 80m, dash again, 110m.
You're a monk, so you took three levels in thief. Two bonus actions.
Step of the wind, dash 140m
Step of the wind, dash, 170m
You can now jump all across the battlefield at absolutely no cost, dealing damage to everything around.
I haven't tested this on high level, yet - I'm only level 4 on my game. But the jump thing works on a monk, you don't need proficiency.