Bewitch is a keyword added August 11, 2011.
Example: "Bewitch Creature. Bewtiched creature loses 50 HP each turn."
When a spell says "Bewitch," this means that the spell stays on the card until it is destroyed, or a counter spell is used. This is used for gradual effects instead of just doing something like: "Destroy target creature."
Bewitch spells are not always negative.