Thunderstaff

Oracle Text

As long as Thunderstaff is untapped, if a creature would deal combat damage to you, prevent 1 of that damage.

2, T: Attacking creatures get +1/+0 until end of turn.

Card Rulings

12/1/2004 If Thunderstaff is untapped, it prevents 1 damage from each creature, each time it would deal combat damage to you. So if three creatures with double strike attack you and aren’t blocked, Thunderstaff will prevent a total of 6 damage.