I remember reading somewhere how the grappling rules are easily abused with the right character.
- 2 levels into Moon druid
- 1 level into barbarian
- Transform into Brown Bear
- Multiattack means you can grapple+attack
- Two arms means you can grapple two people
- Knock prone using unarmed strike (with legs)
- Use bite attacks while grappling two people
- Enemies knocked prone and can't get up (can't spend half their speed to get up since grappled makes speed=0), can't hurt you or beat your athletics check (barbarian rage+ disadvantage from prone) while each of your attacks (and allies' melee ones) have advantage.
While ridiculous, does that have any RAW reasons it wouldn't work?