I have Hannibal Necromancer on the field with 1 spell counter. It is my opponent's turn, and he activated the (previously-set) trap Horn of the Phantom Beast. Can I remove the spell counter from Hannibal Necromancer to target and destroy Horn of the Phantom Beast?
I'd say it's an ignitiion effect, but the rule book isn't too specific, what a quick effect has to look like. (http://www.google.de/url?sa=t&rct=j&q=&esrc=s&source=web&cd=5&cad=rja&uact=8&ved=0CDwQFjAE&url=http%3A%2F%2Fwww.yugioh-card.com%2Fuk%2Frulebook%2FRulebook_v9_en.pdf&ei=3I7PVJGeGouuU_PSgKgC&usg=AFQjCNGA0UwHs5645XFrSUxvPPOOj30lxA)
So you're not able to activate it during your op. turn.