Naya Battlecaller1RGGW
Creature - Elf Soldier
Haste, lifelink
When Naya Battlecaller enters the battlefield, put two 1/1 green Elf Warrior tokens onto the battlefield. Battalion - Whenever Naya Battlecaller and at least two other creatures attack, creatures you control get +3/+3 and trample until end of turn.
3/3
Wingthresher2GUB
Creature - Elemental
When Wingthresher enters the battlefield, target creature gains flying until end of turn.
When Wingthresher enters the battlefield, destroy target creature if it has flying.
4/4
Encapsulating Mirror
Artifact - Equipment
Equipped creature has the abilities of each creature on the battlefield.
Equip :xmana:, where X is the total converted mana cost of creatures on the battlefield.
Although you haven't seen this exact color combination, we have seen mixings before (Slave of Bolas) and the easy way to figure this out would be:
1) X
2) Colorless
3) Hybrid
4) Hard colors
So we're looking at: (U/R)(R/W)WUR (very close to the original post, however the original didn't have the hybrid before the hard colors.
I did note that :symru::symrw::symr::symw::symu: was also a possibility. Also, Wizards lists the enemy color first in a wedge, like Lightning Angel or Numot, the Devastator.
Experimental CommandUURR
Instant
Choose two - Counter target spell; or return target nonland permanent to its owner's hand; or destroy target land; or draw two cards and discard one at random.
Next: WUR(U/R)(R/W)
(and if thats in the wrong order correct me.)
There's no standard for that sort of mana cost. I would probably do it this way:
Angel SparkmageU(U/R)R(R/W)W
Creature - Angel Wizard (M)
Flying, vigilance, haste
Whenever you play an instant spell, Angel Sparkmage deals damage equal to its converted mana cost to target player. You gain that much life, then draw a card.
5/6
Creature - Elf Soldier
Haste, lifelink
When Naya Battlecaller enters the battlefield, put two 1/1 green Elf Warrior tokens onto the battlefield.
Battalion - Whenever Naya Battlecaller and at least two other creatures attack, creatures you control get +3/+3 and trample until end of turn.
3/3
Next: 1BRRG
Creature - Troll Assassin
Deathtouch, reach
When Golgari Assassin dies, you may destroy target permanent.
1/1
Next: WWWW
Instant (C)
Target creature gains lifelink until end of turn.
Draw a card.
Next: (U/R)
Sorcery
Exile all creatures. Draw cards equal to the number of creatures exiled this way.
Next: 1WUR
Creature - Elemental
When Wingthresher enters the battlefield, target creature gains flying until end of turn.
When Wingthresher enters the battlefield, destroy target creature if it has flying.
4/4
Next: (2/R)(2/W)(2/U)
Sorcery
Search your library for a land card and put it onto the battlefield tapped. Then shuffle your library.
Amazingly, this effect has not been done. The closest is Reap and Sow.
Next: xBG
Creature - Bird (C)
Flying, haste
2/1
Next: U(R/G)
Sorcery
Great Flood can't be countered.
Destroy all creatures without flying.
Next: UUBB
Artifact - Equipment
Equipped creature has the abilities of each creature on the battlefield.
Equip :xmana:, where X is the total converted mana cost of creatures on the battlefield.
Next: 2B
Instant
Prick deals 1 damage to target creature or player. If was spent to cast Prick, draw a card.
Next: 2B
Next: 2U
Instant
Return target permanent to its owner's hand. Backlash deals damage to that player equal to that permanent's converted mana cost.
Next: 2WB
I did note that :symru::symrw::symr::symw::symu: was also a possibility. Also, Wizards lists the enemy color first in a wedge, like Lightning Angel or Numot, the Devastator.
Experimental Command UURR
Instant
Choose two - Counter target spell; or return target nonland permanent to its owner's hand; or destroy target land; or draw two cards and discard one at random.
Next: BBGG
There's no standard for that sort of mana cost. I would probably do it this way:
Angel Sparkmage U(U/R)R(R/W)W
Creature - Angel Wizard (M)
Flying, vigilance, haste
Whenever you play an instant spell, Angel Sparkmage deals damage equal to its converted mana cost to target player. You gain that much life, then draw a card.
5/6
(U/R)(R/W)RWU could work too.
Next: B(B/G)G(G/U)U
Instant
Put a +1/+1 counter on target snow creature. Target non-snow creature gets -1/-1 until end of turn.
Next: (U/B)(B/R)