#Moxtober 13: Guarded

During the month of October is #Inktober! Each day has a single-word prompt, but instead of inking something, I design a Magic: The Gathering mechanic to fit the word. This is called #Moxtober.

(#Moxtober was previously named #Meltober, named after "Mel", the more mechanically-inclined counterpart to "Vorthos" of the aesthetic profile spectrum.)
Day 01: "poisonous"
Day 02: "tranquil"
Day 03: "roasted"
Day 04: "spell"
Day 05: "chicken"
Day 06: "drooling"
Day 07: "exhausted"
Day 08: "star"
Day 09: "precious"
Day 10: "flowing"
Day 11: "cruel"
Day 12: "whale"

Today's prompt is: "guarded"

I'm not sure how prevalent we want this guard ability to be in a Limited environment. There have been mechanics in modern design that only exist at uncommon rarities and higher, and that could be an option for guard, if necessary.

This is basically flash plus. If you're able to make strictly-worse keyworded mechanics (jump-start vs. flashback), then you can also make strictly-better keyword mechanics. (Shroud vs. Hexproof, Hexproof vs. Hexproof from black/white, etc.) Of course, all you gotta do is cost the card as appropriate.

While flash appears most in blue and green second-most - all colors have access to flash. The extra effect of redirecting targeted spell/ability is where some colors might be restricted.

For white, this plays into white's access to protective effects. For blue, this plays into its ability to fight effects while they're on the stack, whether it's manipulation or counter, etc. This changing of targets is also a red thing. For green and black, this changing of targets isn't as appropriate. But since green gets flash secondly, perhaps guard is tertiary green.

So, I'd put this mechanic at primarily white and blue in a set with sprinkles of red, green, and black, probably one cycle of guard where it appears at all colors.