You can summon and control very powerful tentacles from the ground around you. You can summon tentacles within 20 meters of yourself, and control them within 300 meters. If they remain out of your control for too long, they will begin to starve.
By default, the tentacles look like those of an octopus, but you can change that as long as it's biologically feasible.
If you do it in the water, you can summon and control a Kraken, but only one at a time. The Kraken can sustain itself with food if not in your range, and acts similar to an octopus.