Thanks to Jack V over on Nightmare Lurker, I'm pondering evergreen keywords. I'll be attempting to design one that fits most of the criteria I listed there. This is my first attempt, but I think it's too complex to be the solution. It may also work out too similarly to deathtouch.

My edit comment was meant to say "tertiary in white."

Oh, interesting. I sort of agree with both halves, that I like how this sounds, but also, it's pretty close to just "deathtouch".

Would be cleaner, and more suitable to be evergreen without the "by a creature of greater power" clause; but then it has potential downsides.

Interesting design-space ones "I built a coward!" but nonetheless downy sidey ones.

As it is... it's deathtouch against red, black, much of green - but not white or blue, or walls or treefolk. Which is kinda interesting too. But it is probably too much a mechanical overlap to be evergreen.

So maybe accept it has a downside?

Looking back, I see that this is too complicated to be evergreen, and perhaps too complicated in general.

I still like it though. Saying "you may have this" instead of "when greater power" might simplify it a bit. Or letting it copy the power of any blocking creature would complicate it but make it more different.

It could potentially be "This assigns combat damage equal to the highest power among blocking creatures."