Death's ember march

As you cast this spell you choose a creature you can see within 150ft to lock onto, you gain half that creatures natural walk, flight, and swim speed as a bonus to your own, additionally you gain an extra 1d12 fire damage to your melee attacks and on each successful melee attack on a single turn you gain +4 to dmg.

(ex: S,S,S,S,S=+0+4,+8,+12,+16 & S,S,F,S,S=+0,+4,+0,+0,+4)

Other features of this spell allow you to never lose the targets location as long as the spell is active and the target hasn't left the 150ft range. You can only move toward the target using the most direct rout possible and or away in a straight line.