Terra Magica

You draw a sigil upon the ground beneath you that raises the strength of magic in a 10-foot radius sphere. Whenever acreature within the area rolls damage for a spell that it casts, the damage increases by 1d4.
At Higher Levels.
When you cast this spell using a spell slot of 4th level or higher, the damage die size increases for every 2 slot levels above 2nd; 1d6 at 4th level or higher, 1d8 at 6th level or higher, and 1d10 at 8th level or higher