Earth Bound Skeleton

A skeleton with a deep blue glow radiating from its bones will be summoned where the caster touches. The caster has to touch something related to the ground e.g. rock, sand, dirt, bricks, slate. It will charge at a chosen enemy ignoring all other enemies and when within 5 feet will self destruct for 1d6 necrotic damage and 1d4 knock back 1- 3ft 2 - 6ft 3 - 10ft 4 - 15ft. If within 3 or less feet of an enemy roll knock back with advantage.