One thing I've noticed about Opportunity is that it says that only ONE opportunity can be active at a time.. That is not entirely true. While using Water Blast power set. When both the Aqua Blast (Offensive) and Hydro Blast (Defensive) are available to fire off, When I fire off the Defensive first (longer cast time) and click the Offensive as fast as possible while the Hydro is still casting both land at the same time and I get both OFFENSIVE AND DEFENSIVE BUFFS at the same time. I've done it multiple times. Some powers may be able to do it besides Water Blast but I haven't tried them all. I do know that I have not been able to do it with Fire.