Pendulum Effect:

You can target 1 Fusion, Synchro, or Xyz Monster your opponent controls; negate its effects until the end of this turn, then destroy this card. You can only use this effect of "D/D Dog" once per turn.

Monster Effect:

Once per turn, if your opponent Special Summons a Fusion, Synchro, or Xyz Monster(s) (except during the Damage Step): You can target 1 of those monsters; this turn, that face-up monster cannot attack, also its effects are negated.