Rulings

If Slaughter Pact is countered or otherwise doesn't resolve (perhaps because its target became illegal), the delayed triggered ability that threatens you with a game loss won't trigger at the beginning of your next upkeep.
If Slaughter Pact resolves with a legal target but the target is not destroyed (perhaps because it has indestructible or regenerated), the delayed triggered ability will still trigger at the beginning of your next upkeep and you will have to pay the cost or lose the game.
Although originally printed with a characteristic-defining ability that defined its color, this card now has a color indicator. This color indicator can't be affected by text-changing effects (such as the one created by Crystal Spray), although color-changing effects can still overwrite it.