I wanted to make some sort of cycle to show that, with blue missing, the enemy color pairs are slightly different. White and Red are enemies, and Green and Black are enemies. The pentagram becomes a square.
I also see blue as being the ally color to each other color.

...If you want to show the enemy colour pairs are slightly different, then I don't see why you'd pick to focus on the two enmities, which are after all still enmities in five-colour Magic land. Green and black are already enemies. AFAICT the only change to colour relationships is that white and black are now allies.

I think my point in showing enemies is to point out that each color now only has one, rather than two.

Hmm. I'm not sure that'll particularly come across, because not all colour hosers are in fully paired cycles.

That's true. I might remove the protection and just leave these opposed in abilities, since I think I'll make counters a minor theme of the set.
I wonder what I might do to convey the slightly different color relationships.

For reference, the cycle is currently Sunwall Healer, Scorchwood Robber, Chasm Guard, and this.

Oh, I see, it's rather tighter than I realised. OK, that's probably fine then.

Oddly, if I make this a -1/-1 counter block, this and Scorchwood Robber should probably have their abilities switched.