Say I have {Azor's Elocutors} with 4 counters and my opponent ends his turn. When it reaches my upkeep, does he have sufficient time to kill the creature with any instant/ability before the 5th counter gets dropped?
Of cos, he could have killed it during his turn but I'm just making a situation. Just a thought process.
Yes. When the counter goes on stack, players get priority(Active to non-active players). He can kill the creature then, placing his kill on top of the counter on the stack
That would just be mean.