Here's a few random ideas I have:
- A spell which allows you to give one of your permanents to your opponent
Possible uses: Use mostly entropy deck and give them a discord at the right time so you can play a few cards of other colors.
Give them a sanctuary to break their dissipation shield
Give your shield or weapon to replace the one they are using with something less useful
Fill all their slots with something useless so they can't play what they want(probably would be difficult to pull this one off but you never know..)
- Red Queen: X/2 Creature that deals 1 damage every turn to all creatures in play(including otherwise untargetable ones?). Pay
to give it +0/+1. "It takes all the running you can do, to keep in the same place."
- Eyes of the Oracle: Permanent that lets you see your opponent's hand and/or the next card you will draw
- Mortar - works similar to Catapult but designed for use with smaller creatures instead, would be especially fun to use in a Pestal deck