Whenever you cast a spell w/ cmc = to the # of doom counters on ~, deal damage to critter or player = to the # of doom counters on ~, then put a doom counter on ~
Mount seems a tad off, IMO. Flavorwise it is odd that multiple creatures can mount the same guy, and riders and mounts can attack independently, mechanically it seems to present a tracking issue. You could try doing something more along the lines of soulbond, or a variant on vehicles, where the rider could tap and give the mount a bonus. Another possible idea is to have the mechanic occur on the rider side e.g.
Raptor Rider 3gg
Creature-Human
Mounted 3 (~ ETB w/ 3 +1/+1 counters. Remove 3 +1/+1 counters from ~, create a 3/3 green dinosaur token)
1/1
BTW: Sunscourge champion is new. It is the white one from the Earthshaker Khenra cycle.
Because everything is.
It said any lands when I posted it. Did you not trust my impeccable phrasing?
Basically sums up the set.
Srocery
Search for upt to two lands. Put them in play tappped.
then if control 3 or more desererts
creeate 2 2/2 sombie tkoens.
2r
Enchantment
ETB w/ a doom counter.
Whenever you cast a spell w/ cmc = to the # of doom counters on ~, deal damage to critter or player = to the # of doom counters on ~, then put a doom counter on ~
Raptor Rider 3gg
Creature-Human
Mounted 3 (~ ETB w/ 3 +1/+1 counters. Remove 3 +1/+1 counters from ~, create a 3/3 green dinosaur token)
1/1