Metabot's Manual of Magical Maneuvers

Bestial Brand

3-level Enchantment

You touch a beast or monstrosity at least one size larger than you and bind it to your will as a mount. Roll 8d8. If the creature's remaining hit points are less than this roll, you can clamber onto the creature as part of the action used to cast the spell. As long as you keep one hand on the mount and its hit points are below your roll, it is charmed by you and you can control the creature as your mount which accepts you as a rider.
You can use your action to take total and precise control of the target. Until the end of your next turn, the creature takes only the actions you choose, and doesn't do anything that you don't allow it to do. During this time, you can also cause the creature to use a reaction, but this requires you to use your own reaction as well.
At higher levels: When you cast this spell using a spell slot of 4th level or higher, roll an additional 1d8 for each slot level above the third.