Lik,
My artificer friend, and my Tortle buddy. If you are reading this, or if someone is reading it to you, you discovered I made your arm mechanical. Shut up, stop! stop freaking out. As a gift, and putting our differences aside. we made it when you were sleeping here at the guild hall. It appeared as flesh. cool huh. well, it was your flesh once. STOP. Stop screaming. Once you used it for the first time the flesh ripped and will remain ripped exposing mechanical features. surprise! a belated gift. Your hand turns into a cannon that shoots a blast of water at a really high pressure from the water reserved inside you. Be careful it most likely kicks hard and lets off a steam after using it. Arameia is probably big mad at us. Oh well. SO. Here is how you use it.
You activate it saying your favorite saying "no witness". Like saying a spell. When used you can point it at the... witness you want to shoot. It will shoot out up to 30 feet of the water at a really high pressure. The witness has dodge (make a DEX save which is (8 + your CON modifier + your Proficiency modifier). If they fail, they will be hurt very bad. (1d10 bludgeoning damage.) If they pass, they still get hurt but will still be alive. (half damage)
Now Lik. it gets stronger as you progress. (1d10) at first, at 5th level its (2d10), 11th (3d10) and at 17th (4d10).
You can only use it once per turn as a FULL ACTION. Like your spells, and you only have enough water to use it a certain number of times. (your proficiency bonus.) If you want to keep it working you must take a long rest. When you wake up to keep it filled you must drink water. You're a Tortle after all, it'll dehydrate you (1 lvl exhaustion). (Dice equal to proficiency bonus +1).
I'm sure you're excited about it now, and thinking of shooting Spiff with it as funny that would be, don't. So stop pointing it at him. The pressure of it will hurt, bad. Though, you being sneaky with it will be impressive, but once you use it everyone near by will know because its loud when you use it. Got to do it at least once.
Now buddy, go leave no witnesses for us. --Tessa
Enjoy and have fun with your new feature my friend. -- Coilbert