Good idea!
I wonder how it would work with Zooids from other Siphos around - it might be too powerful as a holder. Although we could always say other Zooids are more "slippery" than stationary rocks. Also state as a toggle might get weird, but if we do it as we do with Flail - global for whole Sipho, it should be okay. I will write this down and propose it as a prototype for next potential Zooid drop.
Thanks for considering my idea! You also nailed the method which it will toggle (which I forgot to mention), i.e. global for whole Sipho like flail.
And yeah...it was designed to be a little bit on the overpowered side, but in my mind, it was to balance out the fact that it only becomes powerful when active and anchored. After all, it's fragile dead weight when it isn't anchored! Nevertheless, I'll leave the balance to you guys, since you will be the ones to playtest the prototype if it does come to fruition. I'm just glad that my suggestion helped!
