I'm not sure why you think this is any good or would require anyone to rebalance an encounter at level 16. The charmed condition is just:
- A charmed creature can't attack the charmer or target the charmer with harmful abilities or magical effects.
- The charmer has advantage on any ability check to interact socially with the creature.
Like okay, a single humanoid in an encounter has to attack a different party member for two turns worth of actions?
Hypnotic Gaze is such an awkward way of achieving this as well. You've invested two levels in a class with little synergy with your main for an incapacitate that only works with 5 feet of you. Your DC for this is going to be terrible as it's INT based not CHA based. You'd be better off just taking Hypnotic Pattern as a spell.