My cat’s attack action:

Get Underfoot (Refresh 2-6). The target must succeed on a DC 20 Dexterity saving throw. On a failed save, the target falls prone, and probably smashes their head on something dangerous, doing 22 (4d10) bludgeoning damage. On a successful save, the target takes half damage and regrets getting a cat in the first place until they finish a long rest.

And that's how house cats can kill 1st-level wizards in 5e.

— Shawn Merwin (@shawnmerwin) February 10, 2022