Technically B then hold Shift. It will keep the gem bomb selector on and use the top left most gem in your inventory for bombing by duplicating its cost. It wont use the gem up and instead draw straight from the mana pool based on that gems value. So if that gems is a T4 valued at 1100 mana. Pressing B then holding the shift and clicking will gembomb or enrage the highlighted wave as if you were bombing it with Tier 4 gems and you will be charged 1100 mana per bomb.
I've done macro that clicks for me 10 times, so I just press b, then shift+f7 a couple of times. I won't tell you how to do it on windows, becouse I use linux with KDE and it's system function there.
Technically B then hold Shift. It will keep the gem bomb selector on and use the top left most gem in your inventory for bombing by duplicating its cost. It wont use the gem up and instead draw straight from the mana pool based on that gems value. So if that gems is a T4 valued at 1100 mana. Pressing B then holding the shift and clicking will gembomb or enrage the highlighted wave as if you were bombing it with Tier 4 gems and you will be charged 1100 mana per bomb.
You are the man. This had made my life so much easier