--Can you use the discard ability of a card you've already played?
--Having face-up discards and face-down discards in the same pile can be messy. Have you considered showing opponents a "discard ability" then discarding it face down?
--Strongly recommend that your setup picture include a doted rectangle showing that the discard pile is placed horizontally next to the draw pile. I can see lots of mistakes drawing from the discard pile unless it is differentiated from the other 6 choices.
--"Reactions that are Discard Abilities you use on another player's turns do not count TOWARD THIS LIMIT." As written, some may misconstrue this sentence as meaning the cards have no effect.
--Your "additional notes" section is very helpful.