Cheapest priced copy (Alliances): $2.79 at Card Kingdom, near mint, their price list as of .
Sustaining Spirit 
Creature — Angel Spirit · 0/3 · Rare · Alliances · #18
Cumulative upkeep {1}{W} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
Damage that would reduce your life total to less than 1 reduces it to 1 instead.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
1 printing · $2.79 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Alliances | 18 | Rare | $2.79 | — |
7 rulings from Wizards of the Coast
- 4 October 2004Does not affect damage if you are already at zero or negative life. You still take it all.
- 1 October 2008If an effect asks you to pay life, you can’t pay more life than you have.
- 1 October 2008Paying cumulative upkeep is always optional. If it’s not paid, the permanent with cumulative upkeep is sacrificed. Partial payments of the total cumulative upkeep cost can’t be made. For example, if a permanent with “cumulative upkeep {1}” has three age counters on it when its cumulative upkeep ability triggers, it gets another age counter and then its controller chooses to either pay {4} or sacrifice the permanent.
- 1 October 2008The ability doesn’t change how much damage is dealt; it just changes how much life that damage makes you lose. An effect such as Spirit Link will see the full amount of damage being dealt.
- 1 October 2008Sustaining Spirit won’t prevent you from losing the game if your life total is 0 or less or some other effect causes you to lose the game.
- 1 October 2008The second ability is not a prevention effect. It stops unpreventable damage from reducing your life total below 1.
- 1 October 2008The second ability applies only if your life total is being reduced by damage. Other effects or costs (such as “lose 1 life” or “pay 1 life”) can reduce your life total below 1 as normal.