Grab your Urza's lands and your deck will have the huge mana it needs to cast a Karn
I am particularly fond of Reprocess for turning large numbers of Squirrels into large numbers of cards
Kraum, Ludevic's Opuss ability puts pressure on your opponents in two different ways: play more spells each round since the more they hold onto them to play later the more cards you get, OR : hold off on playing more than one spell a turn to keep from giving you any card advantage
On the one hand it does not power up your delve, threshold, flashback etc but on the other hand it gives you much more safety and ultimately information
The Magic: The Gathering card Winged Hive Tyrant has seen a pretty neat little price bump, jumping from the cheap and cheerful $0.80 one month ago to $3.60 today
Shes like a planeswalker in that respect, except shes indestructible and if you play enough stuff shell turn into a creature and join the assault herself