Direct damage

Burn generally refers to a spell or ability that deals direct damage, that is, damage to a target player or creature. Burn spells are most commonly used in aggro decks, and have a low mana cost.

Pure burn decks tend to suffer in the mid-game, when spells have been used up, a hand size is minimal, and there are no creatures to block with.

Famous burn spells

Chain Lightning Lightning Bolt Fireball Flamebreak Kaervek's Torch Disintegrate

Incinerate Fireblast Firebolt Burst Lightning Kindle Char, although Flame Javelin is better in mono red.

Other uses

Burn can also be shorthand for Mana burn.