Mirri, Weatherlight Captain and Judoon Enforcers prevent creatures from entering attacking.

When defending player controls [[Judoon Enforcers]] or a tapped [[Mirri, Weatherlight Duelist]] attacking creatures with mobilize (such as [[Dragonback Lancer]] or effects like that of [[War Effort]] will create tokens but they will not enter attacking and a Game Message will pop up saying "No more than one creatures can attack {playername}"

Reproduce the scenario with Judoon Enforcers or a tapped Mirri, Weatherlight Duelist and a mobilize effect such as Dragonback Lancer or War Effort. Trace the attack-declaration handling that creates mobilized tokens; done means the tokens enter attacking without the "No more than one creatures can attack" game message.

Written by the indexing model from the issue text.