Damage that would reduce your life total to less than 1 reduces it to 1 instead.
Morph (You may cast this card face down as a 2/2 creature for . Turn it face up any time for its morph cost.)
If your life total is less than 1 but you've somehow avoided losing the game, Fortune Thief's effect won't apply at all if you're dealt damage.
16-03-2018
wotc
Fortune Thief's effect applies only if your life total is being reduced by damage. Other effects or costs (such as losing or paying life) can reduce your life total below 1 as normal.
16-03-2018
wotc
Fortune Thief's effect is not a prevention effect. It stops unpreventable damage from reducing your life total below 1.
16-03-2018
wotc
Fortune Thief doesn't change how much damage is dealt; it just changes how much life that damage makes you lose. Abilities such as lifelink will see the full amount of damage being dealt.
16-03-2018
wotc
Fortune Thief won't prevent you from losing the game if your life total becomes 0 or less or if some other effect causes you to lose the game.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.