From the official Japanese Twitter account.

Archnemon

Card NumberBT3-086Level5
Card TypeDigimonPlay Cost7
ColorPurpleEvolution Cost3 (Purple or Green)
Digimon TypeDemon BeastDP6000
AttributeVirusRarityCommon
StagePerfectArtistTSCR
Main Effect[When attacking] By getting -3 Memory, you may play a “Belial Vamdemon” from your hand without paying the cost. Then, destroy this Digimon.
Source Effect

Mummymon

Card NumberBT3-087Level5
Card TypeDigimonPlay Cost7
ColorPurpleEvolution Cost3
Digimon TypeUndeadDP7000
AttributeVirusRarityCommon
StagePerfectArtistTSCR
Main Effect[When attacking] By getting -3 Memory, you may play a “Belial Vamdemon” from your Trash without paying the cost. Then, destroy this Digimon.
Source Effect

Booster Set 3: UNION IMPACT will launch in Japan October 30th, 2020. The cards from it will be combined with NEW EVOLUTION and ULTIMATE POWER for the English format, spread across Special Boosters 1.0 and 1.5.