The elemental being could feel the draw of his home realm. His stay here would be short, but his master bid him to strike down this huge beast. It threw all its strength behind one mighty slam.
1d20 + 6 - 1 ⇒ (16) + 6 - 1 = 21
1d6 + 4 + 2 ⇒ (3) + 4 + 2 = 9
It dissipates on my next round