It is a long time since I used one of these boosts  so I cannot remember what is supposed to happen, so at this stage I do not know if it functioned as it should. So asking for guidance.

Today 5th June  there was  already a game  bonus of -10% and because I was planning  attacking a lot of invaders  decided to also use one of the other boosts . -20% for 1hr. 

I think I didn't get any added  bonus, but for the moment cannot be sure of this.

I was using sustained attack and each attack cost 242 units of energy.

Part way through a series of attacks , the boost ran out and it still cost 242 units of energy for each hit.

It is now 6th June, and I have just attacked an invader and the one hit cost 263 units of energy.

As I cannot ,can some one  reconcile the mathematics for me please?