The Subterror Promo has finally been revealed via the official OCG site
VJMP-JP138 サブテラーの導師 Subterror no Doushi (Subterror Guru)
Level 4 EARTH Dragon Flip Effect Monster
You can only use each of this card name’s effects once per turn.
(1) FLIP: You can add 1 “Subterror” card from your Deck to your hand, except “Subterror Guru”.
(2) You can target 1 other face-up monster; change that monster and this card to face-down Defense Position. This effect can be activated during either player’s turn, if you control another “Subterror” card.