A rainbow draft is a nice format for a Dice Masters event. Each player gets to open 12 booster packs (always fun) and choose cards from among the packs that all the players opened. (Details). Players make a tournament-legal team from their drafted cards and any 2 Basic Actions from their collections, and then play some games.
With the draft format, players can't use the deadly Super Rare cards from their deep collections, so the format tends to be a little more even than fully-constructed tournaments. It's also an excellent way to fill in holes in your card collection. But there are a few strategies to keep in mind:
Draft multiple cards for character you intend to play, because that's the only way to populate your character card with multiple dice.
Plan for characters with a range of costs. Support higher-cost characters with lower-cost ones of the same energy type. On more than one occasion, I've been unable to buy the high cost characters that I needed because I didn't have the correct energy type showing.
Unless you're drafting from Uncanny X-Men boosters, you won't see any of those Professor X cards with the economy-generating global action. If you're used to relying on PXG, keep in mind that you won't be able to buy expensive characters as quickly without it.
You can fill in strategy gaps in your team with your Basic Actions. For example, if you have some expensive character to buy, try Gearing Up. Or if you're short on low-cost characters, bring 2- and 3- cost Basic Actions. (Be careful not to overload your dice bag with Actions; you'll still need typed energy to buy characters.
Keep an eye on drafting cards to fill in your collection. You probably always want to keep those Super Rare cards with the red stripe. And if you still need more Storm dice in your collection, you probably want to grab Storm cards when you can. You probably won't be able to draft to both win the tournament and fill up your collection, but both strategies have their benefits.