Card Name: Switchover
Color: U
Cost: 2UU
Type: Enchantment
P/T:
Rules Text: 2U: Shuffle target non-land permenent into owners library, target permenent's controller draws a card.
GU, Sacrifice <THIS>: Each player shuffles lands they control into the owner's library, each player draws cards equal to the number of lands they controlled that were shuffled into a library, each player may put all lands from their hand into play tapped.
Flvor Text:
Rarity: R
Card Name: Sack of Bones
Color: B
Cost: 2BBB
Type: Creature - Skeleton
P/T: 3/3
Rules Text: Fear.
Whenever an opponent sacrifices a creature, put a +1/+1 counter on <this>
If the number of +1/+1 counters on <this> exceeds the number of swamps you control, sacrifice <this>. If you do, all opponents lose five life.
Flvor Text:
Rarity: R
Ok.
I like Switchover, since it's a bounce enchantment that lets opponent cycle through their deck (if you use it too much) and then you can set up for the Armegedon-like sac ability.
Sack of Bones is good, and works off of your opponent's action (unless you make them sac). It also has a limiting factor.