Burn.

If a source would deal damage to a permanent or player, it deals double that damage to that permanent or player instead.

+1: Chandra Nalaar deals 1 damage to target player or planeswalker. −X: Chandra Nalaar deals X damage to target creature. −8: Chandra Nalaar deals 10 damage to target player or planeswalker and each creature that player or that planeswalker's controller controls.