Custom Entity Attack speeds

I think one of the reasons PvE combat seems a little bland (especially melee) is because melee mobs constantly attack when you get within range. I wish there was an attribute for mob attack speed so you could reasonably block mob attacks with a shield and counter their melee rather than just having to attack them once they cross into your reach range. I think it would be interesting to have a combat scenario where you're going up against a mob with a strong weapon and you have to time your hits and shield in order to slowly chip away at their health.