You may remember me from my quest to make Sligh decks of each color. Well, I've abandoned that. I'm sorry, but Blue really isn't aggressive enough, Artifact Sligh is now reffered to as "Affinity", and I'm just no good with Black. So instead, I give you my take on Spellbinder.

Imprint-When Spellbinder comes into play, you may remove an Instant card in your hand from the game.

When equipped creature deals combat damage to a player, you may copy the imprinted instant and play it without paying its mana cost.

Now, this looks great, but upon further thought, you have to realize that some instants are better used here than others. For example, Fog would be useless, as it resolves after damage has been dealt. Use some sense in choosing a creature to equip as well; without evasion, the instant will rarely resolve at all. So I've done some digging, and found some good instants of each color for Spellbinding.

Red-- Now, the obvious choice here is burn spells. But which burn spells? Everyone says Lightning Bolt is the best, but be on guard; the Bolt's fame is its low casting cost, which you wouldn't have to pay anyway. In this case, a bigger blast is in order, such as Firestorm, Lightning Blast, or even Searing Wind(8R for 10 damage!). A Spellbound Searing Wind puts your opponent on a short clock indeed. Also consider Fissure, which can destroy a creature or a land.

White-- Most instants here involve preventing damage, which in this case is a moot point. Consider Errand of Duty, as the token comes into play at the end of your turn, and also life gain instants to keep you in the game. Remember; equipped to a creature with low power and good evasion, the instant may be copied several times in a game.

Green-- In green, your best choices are probably Hunting Pack(puts a Beast token into play, and has Storm) or Sprouting Vines(search for a land with Storm). Storm instants are great for Binding, as you can spend all your mana on spells, then attack and let the Storm count all the spells. Also, green has the only instant Decree, Decree of Savagery. With Savagery's high mana cost, you're lucky to cast it once, but Spellbound, it could be cast multiple times at a discount.

Black-- Again, Black doesn't like me, but it seems to me that here your best options are Annihilate, Feast of Famine, Tsabo's Decree, or any expensive creature destruction spell.

Blue-- This is Spellbinder's best color to play in: lots of good instants, and plenty of evasion to get a pinger through over and over. My choices here were Opt or Concentrate, giving a card advantage, or Brain Freeze(another Storm) giving deck advantage. Only problem, these instants are so cheap to cast, you'd need to push damage through several times before you had an advantage over just playing the instant. If you can find a bigger blue instant, let me know.

Multicolor-- this is a pretty broad category, but luckily many multicolor instants are hampered only by their mana costs, so this should work nicely. Simoon and Frenzied Tilling come to mind, along with all the Dragon Legends' charms. Recoil can get annoying fast as well.

3)Storm spells work well, since the mana you would've spent on them can go to building up the Storm.

1) Make sure it can get damage through effectively, but if its power is so high it finishes your opponent off in one or two hits, Spellbinder was a waste of time.