Jevan R. H. Divinitive
This is what it is most likely to be.
The Winged Dragon of Ra
Divine-Beast/Effect/10/DIVINE/ATK ?/DEF ?
You must tribute 3 monsters you control to Normal Summon this card. The Normal Summon of this card cannot be negated. When this card is Normal Summoned, a Spell, Trap, or Effect Monster Card cannot be activated. This card cannot be targeted by the effects of a Spell, Trap or Effect Monster. If this card is Special Summoned, it is sent to the Graveyard during the End Phase. The ATK and DEF of this card becomes the sum of the respective ATK and DEF values of the Tributes. When this card is Special Summoned, you may activate one of the following effects: *Pay 1000 Life Points to destroy one monster on the field and remove it from the game. *Pay all but 1 Life Points, and increase ATK and DEF by the amount of Life Points paid.
yeah, they're most likely using the video game effects, slightly modded.
Obelisks's video game effect is word for word with the effect card version, except for one tiny detail, it cant attack after nuking your opponants monsters. so ra will probally slightly modded to not be removed from play along with the monster it's removing.
slifer probally wont change at all from the video game effect version. after all it's so conditional.
Slifer:
this card cannot not be set. this card cannot be normal summoned ecept by tributing three monsters. this card gains 1000 atk for each card in your hand. when your opponant summons a monster with 2000 def or less, it is destroyed.
Slifer will be the only one who wont be terribad because you can throw in light of intervention to keep them from setting monsters so slifer can just pop them. the best part is, slifer's effect can barely be stopped because of his other effect that prevents being targetted, and almost all effect negating cards target. (exception being skill drain i believe)