From the Depths When you choose this Monastic Tradition at 3rd level, you gain water breathing, and your swimming speed equals your walking speed.

Eldritch Gift Also at 3rd level, your flesh becomes more squishy and moist. You can spend a Ki point to activate your Eldritch Gift, turning your arms into tentacles. While they are this way you cannot hold any weapons, but your reach extends 5ft. This lasts one hour, or until you use a Bonus Action to turn the tentacles back into arms.

Unearthly Blessing Beginning at 6th level, your new flesh serves as a conduit for powers unknown. While your Eldritch Gift is active, you can cast the following spells by their associated Ki point cost, ignoring material components. Ki Spell 2 Arms of Hadar 3 Invisibility 5 Evard's Black Tentacles

Uncanny Grasp At 11th Level, you can add your Wisdom modifier to your Athletics checks, as long as your arms are tentacles. Furthermore, when you have an enemy grappled, you can expend 2 Ki points to detach your tentacles, leaving the enemy grappled. The enemy must pass a Athletics or Acrobatics check equal to your DC to escape.

Your arms immediately regrow as normal arms.