Combos
Gauntlets of Chaos and Unstable Mutation:
The gauntlets let you trade a crappy creature for your opponent's prize, but why stop there? Since the gauntlets destroy enchantments on the targeted critters, first slap yours with the mutation, and wait a couple of turns for it to get -1/-1 counters. When the gauntlets quash the mutation , the counters will kill your traded creature.
Jokulhaups and Living Lands:
Sometimes you need to make everything go boom. Jokulhaups is great for this, destroying everything but enchantments. Of course if your going to blow everything up you'll need a recovery plan, and living lands works well. While your opponent scrambles to get enough land to cast something you'll be pounding him with your land.
Brass Man and Veteran's Voice:
Alone the brass man is a loser who missed the casting call for the wizard of oz, but paired with the veteran's voice he's a creature-pumping manace. During your upkeep, you can use the brass mans untap ability over and over, so activate veteran's voive as much as you can.
Floodgate and Teferi's Curse:
When the floodgate's come tumbling down, all the critters that can't swim get washed away. Well, Teferi must be some kind of twisted jerk, because when he curses a floodgate, he makes sure everone takes regular dunkings. Fortunately, your blue creatures are right at home in the water, while your opponent wishes for a goblin lifeguard or the scuba gear of Urza.
Candelabra of Tawnos and Power Surge:
Sometimes, even the best intentions go wrong. Say, for example, you want to help out your poor opponent, whose land is all tapped out. Well, tap all your land at the end of your turn, and dump the manain to the candelabra to untap his land. But wait...there's a power surge in play! Oops...you just sent your opponent on a one-way trip to hurtsville.
Mind Bomb and Balance:
Drop the bomb,and the scales tip in your favor. Everyone knows how valuable card superiority is, so while you ditch a few cards from your hand to prevent damage from the bomb, your opponent will probably eat the three points of damage to keep his hand size up--- all in vain, because when you drop the balance, he looses his cards anyway.
Shallow Grave and Metamorphosis:
When your short on mana and have a hand full of expensive creatures, all is not lost. Discard one of your high casting cost critters, and drag it back out of the graveyard and into play next turn with shallow grave. Sacrifice that creature to metamorphosis, and you'll have pile of free mana of any color to cast creatures with.