fairy wind

"Destroy all other face-up Spell and Trap Cards on the field. Both players take damage equal to the total number of cards destroyed by this effect x 300"

Secondo fai solo 900 danni visto che l'ultima fairy distrugge 3 carte scoperte ma la penultima non ne distrugge nessuna.

Penso che il tutto rientri in questo caso:

IMPORTANT: When resolving a chain, as the cards resolve they are NOT sent to the Graveyard until the entire chain has resolved, or a card specifically destroys them. This is important for cards such as "Princess of Tsurugi" and "Secret Barrel" where the effect depends on the number of Spell & Trap Cards on the field.

Quindi nel secondo caso, dipenderebbe proprio da ciò che prevedono le trappole X e Y che hai attivato.