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.
2004-12-01
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.