Pyromancer resolves
Tap out for Dust Elemental (6/6, Flash, Flying, Fear, When ~ CIP, return three target creatures I control to their owners' hand)
Stack:
Shaper Parasite
Necrotic Sliver
Dust Elemental
Responses?
Spidey: 10
Hand: 7
In Play:
(T,T) Plains x2
(T) Forest
(T) Mt
(T) Island
(T,T) Swamp x2
Seal of Primordium (Sac ~: Destroy target artifact or enchantment)
Dust Corona (Enchanted creature gets +2/+0 and can't be blocked by creatures with flying)
(T) Prodigal Pyromancer (1/1, T: ~ deals 1 dmg to target creature or player)
(T) Primal Plasma (4/2, flying) *Corona'd*
(U) Shade of Trokair (1/2, W: ~ gets +1/+1 ueot. Suspend 3-W)
(U) Shaper Parasite (2/3, When ~ is turned face up, target creature gets -2/-2 or +2/+2 ueot)
(U) Dunerider Outlaw (1/1, Pro-Green, Aeot, if ~ dealt dmg to Mooseman this turn, put a +1/+1 ctr on it)
(S) Dust Elemental (6/6, Flash, Flying, Fear, When ~ CIP, return three target creatures I control to their owners' hand)
Graveyard:
RFG:
Mooseman: 8
Hand: 8
In Play:
(T) Plains
(T) Island
(TT) Swamp
(UT) Mountain
(T) Forest
(U) Skirk Shaman (2/2 Skirk Shaman can't be blocked except by artifact creatures and/or red creatures.)
(U) Synchronous Sliver (3/3, all Slivers have Vigilance)
(S) Necrotic Sliver (2/2, All Slivers have "3, Sacrifice this creature: Destroy target permanent")
Graveyard: Prodigal Pyromancer, Blightspeaker, Dash Hopes, Ridged Kusite
RFG: