Transmogrify

A creature you can see within range who fails its save (no save if willing, beasts are always unwilling (even if conjured or summoned)) is transformed into hulking monstrous version of itself. It grows to one larger size. Gets a minimum Strength 20, Constitution 18 for the duration of the spell, but a maximum 6 Intelligence. Its body grows fur, scales, horns or the like. Its hands (or front feet) become clawed, allowing it to strike twice for 1d8†+5 slashing damage. The target’s speed increases to 40, and it can leap 30ft. Lastly, the creature always attacks recklessly (advantage on its melee attacks and to all those attacking it). 
The Transmogrified creature will attack the nearest creatures and continue attack until there is no target in sight, or the spell ends. It can use melee and thrown ranged weapons (but not spells (or other magics), bows, cross bows, or other complex weapons).

†d8 for Large creatures, d12 for huge, 2d8 for gargantuan.