Top down Bant card that removes the need for Myriad from the cube. Reference to Mirror-Sigil Sergeant. Amazed I could cram in the highly abbreviated flavour text.

Neither of those abilities can be granted after you attack. You want something like "at the beginning of combat, you may have target creature gain vigilance and myriad until end of turn. If you do, other creatures you control can't attack this turn."

Why have the "in multiplayer"? Why not have the more important facts that myriad is a triggered ability and the correct "other than defending player" (which is not the same as "it didn't attack")?

You have correct reminder text for myriad, but you don't use it.

Dude1818: The second ability is supposed to be static ability that conditionally grants a pair of other abilities. It's supposed to be like Homicidal Seclusion or Orcish Oriflamme. I agree the wording probably isn't correct and the timings a mess but I'm not sure how else it can be worded as a single sentence. It needs to grant the ability to the creature early enough for the abilities to work while specifying the creatures attacking alone. Maybe it could be worded as "A creature you control that's attacking alone has vigilance and myriad.".

SecretInfiltrator: I had to abbreviate the correct remainder text for Myriad because it wouldn't fit on the card. I've try changing it to match your suggestions so it's clearly