Magic: The Gathering - Duels of the Planeswalkers

You win a white deck after beating the second campaign mission. You don't need to unlock any cards for it, the standard deck should work fine.

Go to Custom Duel, and hit X to open the advanced options. Bump your starting handsize up to 9, and the AI's down to 5. It can't hurt to turn the AI down to the lowest difficulty in options, either. Elspeth is a good opponent to use here as her deck is very defensive. If you don't see a lot of lifegain in your hand, don't be afraid to draw a new hand a few times, you won't be able to keep more than 7 in your hand after your first turn ends anyway.

Play very conservatively, leaving everything untapped to block to keep your opponent from attacking and focus on gaining life. Only use Pacifisms on creatues that you can't block and kill. One good combat trick is to block with Goldenglow Moth, then cast Holy Day. The moth won't die, and you'll still gain the 4 life.

This is also boostable in a player match with a friend.

Norvy prefers white it seems, while I tend to stick with the green beasties. Green offers many low cost creatures to block with such as Wall of Wood, Bears, and Armodon. Your larger creatures should drop quickly because of the land advantage cards such as Civic Wayfinder and Rampant Growth, so you shouldn't have a problem fending off their advances.

The Wayfinder and Rampant Growth also help thin your deck out to find the cards your looking for: Wurm's Tooth and Natural Spring. Your base deck comes with two Natural Spring, and by beating the first five levels of campaign you also unlock two Wurm's Tooth.

Wurm's Tooth out early on (especially against a green deck) is an awesome life advantage. It gives you one life for every green spell played by anybody. This will be your slow but steady life gain during the game.

Natural Spring is a one hitter quitter. 5 mana for 8 life. If you've got the Tooth in play you get nine instead.

Now just like Norvy said, play defensively. Save your Giant Growth's to pump up your blockers, and don't bother attacking. Eventually you're going to pull Duskdale Wurm, a 7/7 trample. You're going to want to put a Blanchwood Armor on him to pump him up to 14/14 (or higher) and intimidate your opponent into not attacking. This will allow you time to play more green spells to gain life with the Tooth. It should only take around 10-15 turns with the Tooth out to get up to 30 life, and most of the time you'll pull at least one if not both of the Natural Springs to help bump it up that much more.

Any deck can do this if you unlock the cards that raise your life for playing your respective spells. Teeth of the predator is particularly effective once you unlock some extra cards for it, namely loxodon hammer and the wurm tooths. Play defensively against the first few opponents on mage difficulty, shouldn't be difficult.