The 1st & 2nd effect of Reactor Dragon only works if it was tribute summoned and since tribute summoned no longer relevant, this card is just same as other AG monster. Use Sphere Kuriboh or Hallowed Life Barrier to stall then you can destroyed it with Maximus or suck it with Vamp
Activate Hallowed before the battle phase, you will take no battle damage and also all your monsters cannot be destroyed by battle this turn. Hallowed Life Barrier is great card in current heavy OTK meta
Sphere Kuriboh is useless against Reactor Dragon. As are cards like Shield Warrior (you cannot activate monster effects until the end of the damage step when Reactor Dragon attacks).
Sphere Kuriboh is useless against Reactor Dragon. As are cards like Shield Warrior (you cannot activate monster effects until the end of the damage step when Reactor Dragon attacks).