@@ohoangthien8090 how's that op? It's just Rally with extra (worse) steps. The point of having such a condition-sensitive keyword is to have a bigger outcome than the easiest-to-trigger keyword. Seems pretty eh and slow.
This seems like a terrible mechanic. It requires the opponent to have a troop and have a higher attack value than themselves. Which makes almost zero sense, since they are custodes and most likely have high stats. Unless it is changed to "also triggers if your opponent plays a troop with higher attack" or there are other cards that really synergizes, this mechanic seems too conditional to consider for deck building.
This isn't their only mechanic. There's also exemplar which is basically relentless with extra steps. If you have no other Custodian troop except for said troop. Which showcases their one man killing machine schtick.