CardName: Alliance Dragonslayer
Cost: WGUB
Type: Artifact Creature - Knight
Pow/Tgh: 4/4
Rules Text: Exalted
Unearth {W}{G}{U}{B} ({W}{G}{U}{B}: Return this card from
your graveyard to the battlefield. It gains haste. Exile it
at the beginning of the next end step or if it would leave
the battlefield. Unearth only as a sorcery.)
Flavour Text:
Set/Rarity: Multiverse Design Challenge Rare
For Challenge # 064
What are the ways of making four-colour cards? So far there's even less flavour specific to quads than there is to wedges. One way is to rely on overlaps of two or three colour sets. You could do a Selesnaya+Dimir card, but it would need to need both colours from each guild.
So instead I went to shards, trying to make a Grixis+Naya+Esper+Bant card. This is somewhat convenient because Grixis and Bant can be conveyed by one keyword each, Esper solely by the type, and Naya by growing to 5/5 when it attacks exalted.
I'm not sure about strength, there's little guidance for what you can get for four-colours. It's probably the equivalent of a 6-cost two-colour card? I'm not sure if this is actually right, but it was hard to give it any other stats than 4/4 growing to 5/5.