entity with two different ranged attacks (again)

I am making a boss for a mod that has two attacks, and both are ranged attacks, one of them is a regular ranged attack, and the other is a slower attack that only fires every ten seconds. how do I make that without adding another entity? I already posted this before, but I didn't get an answer that helped. It's a neutral entity, and it needs to attack only when the player is aleady being targeted by the first attack. something that would help is a way to make the entity use the secondary attack every 10th shot of the primary attack, but I couldn't find a way to do that.