Infermon (BT17-055) - Secret Crisis

[When digivolving] [De-Digivolve 1] 1 of your opponent's Digimon. Then, 1 of their Digimon with a play cost of 8 or less can't attack players until the end of their turn.

[All Turns] [Once Per Turn] When another of your Digimon with [Diaboromon] in its name is played, [De-Digivolve 1] 1 of your opponent's Digimon.