It essentially counters any spell or ability that targets the creature with ward unless its controller pays a specified cost
Of course, many Pokedex entries allude to the fact that Phantumps are the souls of dead children possessing tree stumps, so maybe it has something to do with that
Also, LOL Stoneblade Isaiah Cartwright (Arenanet: Guild Wars, Asheron's Call) Bad design
Any damage taken by the Planeswalker character will take some amount of real time to regenerate, such that a player cannot immediately challenge an opponent after a defeat, though the player can use a healing potion, which replenishes over time, to fully heal the character, or can switch to a different Planeswalker to use
If people play Sisay a bit more, it could see some upside