Creatures your opponents control get -1/-1 until end of turn. Exile Festering March with three time counters on it.
Suspend 3—(Rather than cast this card from your hand, you may pay and exile it with three time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, cast it without paying its mana cost.)
6/7/2013 You can exile a card in your hand using suspend any time you could cast that card. Consider its card type, any effect that affects when you could cast it (such as flash) and any other effects that could stop you from casting it (such as Meddling Mage’s effect) to determine if and when you can do this. Whether or not you could actually complete all steps in casting the card is irrelevant. For example, you can exile a card with suspend that has no mana cost or requires a target even if no legal targets are available at that time.
6/7/2013 Exiling a card with suspend isn’t casting that card. This action doesn’t use the stack and can’t be responded to.
6/7/2013 If the spell requires any targets, those targets are chosen when the spell is finally cast, not when it’s exiled.
6/7/2013 If the first triggered ability of suspend (the one that removes time counters) is countered, no time counter is removed. The ability will trigger again during the card’s owner’s next upkeep.
6/7/2013 When the last time counter is removed, the second triggered ability of suspend will trigger. It doesn’t matter why the last time counter was removed or what effect removed it.
6/7/2013 If the second triggered ability of suspend (the one that lets you cast the card) is countered, the card can’t be cast. It remains exiled with no time counters on it, and it’s no longer suspended.
6/7/2013 As the second triggered ability resolves, you must cast the card if able. Timing restrictions based on the card’s type are ignored.
6/7/2013 If you can’t cast the card, perhaps because there are no legal targets available, it remains exiled with no time counters on it, and it’s no longer suspended.
6/7/2013 If the spell has any mandatory additional costs, you must pay those if able. However, if an additional cost includes a mana payment, you are forced to pay that cost only if there’s enough mana in your mana pool at the time you cast the spell. You aren’t forced to activate any mana abilities, although you may do so if you wish.
6/7/2013 A creature cast using suspend will enter the battlefield with haste. It will have haste until another player gains control of it (or, in some rare cases, gains control of the creature spell itself).