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.

The 42nd episode of Bandai’s FUN! DigiCa YouTube channel revealed two Rares from the upcoming third booster set, BT-03: UNION IMPACT.

Belial Vamdemon

Card NumberBT3-092Level6
Card TypeDigimonPlay Cost13
ColorPurpleEvolution Cost5
Digimon TypeDemon LordDP12000
AttributeVirusRarityRare
StageUltimateArtistTANIMESO
Main Effect<<Piercing>> (During the battle this Digimon attacked, and destroyed an opponent’s Digimon, it checks Security)
[During both turns] When another Digimon is destroyed, get +1 Memory for each Digimon destroyed.
Source Effect

Belial Vamdemon has some interesting combo potential with the Fatal Bond keyword, as another Digimon resolving Fatal Bond will cause his controller to gain 2 Memory, 1 for each of the Digimon destroyed. This has potential as an engine for generating enough Memory to play higher-cost cards, though at the moment there are only a small number of Digimon with the keyword.

Dinobeemon

Card NumberBT3-055Level5
Card TypeDigimonPlay Cost8
ColorGreenEvolution Cost3 (Green or Blue)
Digimon TypeMutantDP7000
AttributeFreeRarityRare
StagePerfectArtistsasasi
Main Effect<<Piercing>> (During the battle this Digimon attacked, and destroyed an opponent’s Digimon, it checks Security)
<<Jamming>> (This Digimon is not destroyed by battles with Security Digimon)
Source Effect

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.