Copycat

When another creature you can see casts a spell, you can use your reaction to “copy” that spell. On your next turn, you may use your action to cast that spell as though it were on your spell list. If the copied spell is at a level you can cast, you must spend a spell slot of equal level to cast it.

If it is at a spell level you do not have access to spell slots for (either because you have expended them already, or are not high enough level) you must make a check to see if you are able to cast it. The check is based on your spell casting ability, and the DC equals 10+the level of the spell. Once you make the check, whether it succeeds or fails, you must expend your highest available spell slot.

If the ability check fails, the spell fizzles and has no effect, or the DM can choose to roll a d20 and apply one of the following effects:

1: The spell backfires and you are racked with (spell level)d10 psychic damage

2: The spell backfires and you are racked with (spell level)d6 psychic damage

3: If the spell targeted yourself or an ally, it targets an opponent instead, or vice versa

4: The spell fails and your Intelligence becomes 1 for the next d4 turns

5: The spell fails and you are unable to cast spells or cantrips for the next d4 turns

6: The spell fails and you are stunned until the beginning of your next turn

7: The spell fails, and you receive 1 point of exhaustion

8: The spell fails, and you are confused (per the spell confusion) until the beginning of your next turn

9: The spell fails, and you fall prone

10: The spell fails, with no other effect

11: The spell succeeds, but your Intelligence becomes 1 for d4 turns

12: The spell succeeds, but you are unable to cast spells or cantrips for the next d4 turns

13: The spell succeeds, but you are stunned until the beginning of your next turn

14: The spell takes effect, but 120 feet in a random direction from the original target

15: The spell takes effect, but 30 spaces in a random direction from the original target

16: The spell takes effect, but 10 spaces in a random direction from the original target

17: Choose a target or space other than the one originally targeted, the spells take normal effect

18. The spell succeeds, but takes effect after 1 minute

19: The spell succeeds, but takes effect after 30 seconds

20: You may repeat the check to cast the spell, with another chance for success