And you reveal it with your first card or with the second in a 3 player free for all ?
Do you count that card's RN?
No no, dirty cheat allows you to play a card DURING the draw phase, after everyone has put their cards face down.
So, like this:
1. Everyone places their cards face down, including you.
2. You state that you are going to use Dirty Cheat.
3. You deduct 2 EP for doing so.
4. You pick a spell, and say who it is targeting (RN does not matter).
5. Apply the FX of that spell to your target, EXCEPT for DMG.
So if you dirty cheated with earth, you'd heal 2 HP. If you dirty cheated with ice, you'd reduce your target's EP by 2.