When you conquer with Last Rites, can you hide Teemo from trash?

To answer your question: No, you cannot hide Teemo from your trash.

Reasoning:

1. Last Rites Effect: The effect of Last Rites allows you to play a unit from your trash.
2. Definition of "Play": Playing a unit (Rule 359) is a distinct game action from hiding a card (Rule 421). Hiding is a separate, discretionary action that requires the card to be in your hand or Champion Zone (Rule 421.2.a).
3. Trash Restrictions: The trash is a non-board zone. You cannot perform the "Hide" action on a card while it is in your trash.
4. Last Rites Limitation: Because Last Rites specifically grants permission to play a unit, it does not grant permission to perform other actions like "Hide" on cards in your trash.

In summary, while Last Rites allows you to bring a unit from your trash onto the battlefield, it does not allow you to bypass the requirements for the "Hide" action. You would first need to move the unit from your trash to your hand (or another valid zone) before you could hide it.