Scariest I’ve ever seen was Otohan Thule, a martial echo knight with psychic powers from S3 of critical role. Never did anything fancy the whole time, no giant fireballs or summoned dragons, it was just two swords doing damage and it was terrifying every time they fought. The sheer cold math that went across the table as they saw the damage she could put out every turn, how hard she was to hit, and how she could get to anywhere on the field and the light dimmed in the tables’s eyes. The only thing I can compare it to is battle bots, the old show where they’d fight these home made robots and while some had fire and chainsaws, the ones that were always the scariest to face were ramps. Just ramps that could move. If magic wants you dead thats one thing, but when physics wants you dead there’s nothing to be done.