Succession
$4 Action
You may plan an Action card from your hand twice. Trash it. Gain two copies of a Card costing 1 less than it.
Hopefully fairly clear: Half procession, half stonemason. I think it's possibly stronger as a $4 than as a $3 due to self synergy.
Sanction
$2 Action
Choose one: +2 Cards; or +2 Actions; or +$2
Trash this card. Put a Sanction token on top of a Kingdom pile.
-------
If anyone plays a card with a Sanction token on it: Return it to the supply. Then then choose one per Sanction token: +2 Cards; or +2 Actions; or +$2
Hopefully clear. I'm aiming for something that you can either try to scupper your opponent with (forcing them to return a key engine component to the supply), or help you by building up a powerful one-shot card.
I'm slightly expecting it to be broken in some way though! (it's return to the supply rather than trash to stop it being broken with Fortress)