As a Bonus Action, you can command your vermin to swarm a creature you can see within 30 feet of you. The creature takes 1d6 Piercing damage and subtracts 1d6 from the next D20 Test it makes before the start of your next turn.
At Higher Levels
The damage increases when you reach Warden levels 5 (1d8), 11 (1d10), and 17 (1d12).