He kicked off the wall with his powerful hind legs and lowers his head to crush the mummy into the stone floor.
Charge. If the elk moves at least 20 feet straight toward a target and then hits it with a ram attack on the same turn, the target takes an extra 7 (2d6) damage. If the target is a creature, it must succeed on a DC 14 Strength saving throw or be knocked prone.
Ram. Melee Weapon Attack: +6 to hit, reach 10 ft., one target. Hit: 11 (2d6 + 4) bludgeoning damage.
Rolls
1d20+6 to hit - (1d20+6)
(17) + 6 = 23
charge - (2d6)
(26) = 8
Ram - (2d6+4)
(15) + 4 = 10
cuz I fell. Head first. Onto a mummy. (If DM says so) - (2d6)
(42) = 6