Thaumic Trammel

You manifest the raw weight of magic, forcing one creature within range to make a Constitution saving throw. On a failure, the target takes 1d10 + 10 Force damage for each spell that is currently affecting it (including this one), as well as for each spell that it is holding Concentration.

A creature that takes 30 or more damage from this spell also has the Prone condition.

Using a Higher-Level Spell Slot. The Force damage per spell increases by 1d10 per level of spell slot above 4.