In Monolith Arena, the rules state:
after the tiles have been drawn, the player must DISCARD ONE OF THE THREE TILES into the discard pile.
This is during the player upkeep step, so the sequence of events:
- Draw three tiles
- Discard one tile
- Consider the remaining tiles and potentially play them
Is it against the rules to retract the discarded tile or change your mind, directly after discarding it, without input from the other player(s)? Asking for a friend.