Idea
3
0|1
Adrenaline.
- chroma cost because it's colourless
- card art must be green
- 0 attack because it's asleep
- adrenaline because it sleeps furiously!
This card potentially would have synergies with rejuvenation, mutation/improve, shazam (depending on rarity), and assorted buffs. The 0 attack means it needs something to synergise with, can't just be thrown in like a long sword.
Alternatively (or as a completely-different upped version?), it could be something like 6:chroma for a 0|16 with an active to rage potion itself. But that might be stepping on the toes of too many other extant creatures.
Another possibility is using this concept as a creature that delays itself after attacking, kind of like slaking. A while back I came up with a shark of patience concept that was 6:water for a 10:10 which delays itself on hit, but a colourless green idea with a 'furious sleep' passive could also carry the same build. Not sure how to massage the costs, and it might be too versatile for a chroma card.