Forum:Arcanite/Endymion Citadel Question

hey, i wanna know if i have a loaded up citadel(10 counters), and arcanite on my field, can i blow up my opponents field? im speaking with regards to the "once per turn" part of the card's text.

also if my opponent summons a breaker while i have a loaded citadel, can he use its effect to blow up the citadel?