Monster spellcasting ability casting time

@JeremyECrawford @mikemearls @SageAdviceDnD Does at will spellcasting ability means he can do it each round as an action or as extra action?

— Lexar (@Lexar131) June 30, 2015

If a monster has the ability to cast a spell at will, that spell is cast using its normal casting time. https://t.co/uFAwvrAKxy

— Jeremy Crawford (@JeremyECrawford) July 7, 2015