Get the MTG
Interactive Encyclopedia
from Amazon.com

In response to the earlier spreading plague, there are several other cards
that interact very well with the plague.  Bribery, for example, is
incredible.  Let's see, I'll go through your deck, take the best creature
of the appropriate color, and then wipe out your army.  Ouch!

Or what about either Blind Seer or Distorting Lens, both of which can
change the color of a creature (your's or your opponent's) and annihilate
the opposing army.  This particularly effective with gating creatures like
cavern harpy.  In one game, I brought in one harpy, gated another, used the
lens' ability, and repeated whenever necessary to the clear the board.

While the plague is expensive, if you can get it down with countermagic to
protect it, it can be crushing against creature based decks like rebels or
fires.

James DeVault