Chaddeus' Send-it Sending

You yell at a creature within range and improve its ability to "Send It". Whenever that creature makes an Attack, Ability Check, or Saving Throw, flip a coin instead of rolling a D20. On Heads, the roll is a critical success; and on Tails the roll is a critical fail. This effect lasts on that creature until they have a critical fail on an Attack, Ability Check, or Saving Throw, or until the spell ends.

Using a Higher-Level Spell Slot. You can target one additional creature for each spell slot level above 3.