Frogskin

4th-level biomancy*

Casting Time: 1 action
Range: Self
Components: V, S, M (some frogspawn)
Duration: Concentration, up to 1 minute
Class: Druid, Sorcerer, Tamer, Warlock, Wizard

You morph your skin and clothing into that of a slimy, poisonous frog. Make a melee spell attack against a creature within your reach. On a hit, the target takes 3d10 poison damage and is poisoned until the end of your next turn. Until the spell ends, you can use an action on each of your subsequent turns to make this attack again.

Slimy. For the duration, you have advantage onchecks and saves made to avoid being grappled or restrained, and disadvantage on any attempts you make to grapple a target. Each creature grappling you, or that you are grappling, must make a Constitution saving throw at the start of each of its turns, taking 3d10 poison damage on a failure, or half as much damage on a success.

At Higher Levels. When you cast this spell using a spell slot of 5th level or higher, both damages increase by 1d10 for each slot level above 4th.

*can be replaced with transmutation
Source: Heliana's Guide to Monster Hunting