Mass Teleport is a nice "oh shit-skees" card when the boss aims for a board wipe or you are about to lose a bunch of allies. This card removes them from the game, then the ongoing sets in. It would really suck if this card was destroyed then and there, but you can chain that effect, even in a automated raid of mine and put all those allies back into play under your control. This has the added benefit of healing them, because the allies did not leave play with damage on them. I can see this card fetching quite a price at the tournament level. Definitely play it if it drops as loot or you can find a few copies.