Ob Nixilis, the Adversary (206) [Streets of New Capenna] Synchro/Effect Monster You can only use this

You can only use this effect of "Primathmech Laplacian" once per turn

If either coin is heads

where Origin Forme Dialga VSTAR and Origin Forme Palkia VSTAR shape the very fabric of time and space

or 1 non-Ritual monster that mentions it

Ob Nixilis, the Adversary (206) [Streets of New Capenna] Synchro/Effect Monster You can only use thisRarity: M #: 206 Card Type: Legendary Planeswalker Nixilis Description: Casualty X. The copy isn't legendary and has starting loyalty X. (As you cast this spell, you may sacrifice a creature with power X. When you do, copy this spell. The copy becomes a token.) [+1]Each opponent loses 2 life unless they discard a card. If you control a Demon or Devil, you gain 2 life. [2]Create a 1 1 red Devil creature token with "When this creature dies, it deals I