Clearer text from the official website gives a rougher idea of what Dark Summoning Beast and Diabound Kernel’s effects are. Please keep in mind these are unconfirmed as to 100% accuracy. When we have more clear text, we’ll confirm them.

Diabound Kernel

Level 5 DARK Fiend-Type Effect Monster

ATK 1800

DEF 1200

You can only use (2) effect of Diabound Kernel once per turn.

(1) When this card declares an attack: It gains (?00) ATK.

(2) Once per turn, during either player’s turn: You can target 1 face-up monster your opponent controls; that monster loses ATK equal to this card’s ATK, then banish this card until the Standby Phase of the next turn. This ATK loss lasts until the end of this turn.

Ankoku no Shoukanshin / Dark Summoning Beast

Level 5 DARK FIend-Type Effect Monster

ATK 0

DEF 0

You can only use the (1) effect of “Dark Summoning Beast” once per turn.

(1) You can Tribute this card; Special Summon 1 “Uria, Lord of Searing Flames”, “Hamon, Lord of Striking Thunder”, or “Raviel, Lord of Phantasms” from your hand or Deck, ignoring the Summoning conditions, also monsters you control cannot attack for the rest of this turn.

(2) You can banish this card from your Graveyard; add 1 “Uria, Lord of Searing Flames”, “Hamon, Lord of Striking Thunder”, or “Raviel, Lord of Phantasms” from your Deck to your hand.

Source