Paying a maximum of nine life to save yourself from poison would always be worth it, especially in formats like Commander where you have so much life to work with anyway
Otherwise it would pretty much just be a cost-reducing mechanic
Anyway, I think that these cards are all similar to Gideon above theyre all ridiculous individual cards, but theyre still just not powerful enough to be truly competitive
Its the best way to deal with threats before they hit the board, stopping creatures ETB effects and preventing a player from getting an activation off of their planeswalker before you can kill it in combat
Please use pencil/pen and paper to help facilitate this mini-game
So Cabal Coffers, Urborg, Gaeas Cradle, Field of the Dead even Glacial Chasm