When “Ring of Destruction” or “Call of the Haunted” is chained to “Pineapple Blast”, and the number of monsters on the field is changed, count the number of monsters at resolution of “Pineapple Blast”’s effect, not at activation.
If, when “Pineapple Blast” resolves, you have no monsters, all of your opponent’s monsters are destroyed too.
If you Summon a monster and want to activate “Pineapple Blast”, and your opponent wants to use “Trap Hole”, “Pineapple Blast” is Step 1 of the chain and “Trap Hole” is Step 2.
Netrep Rulings:
“Pineapple Blast” cannot be activated if the player summoning “Marauding Captain” chooses to use the Special Summoning effect of “Marauding Captain.”