When reaching 2.5 A/S on staff, you start casting two projectiles each attack. I have reached it with maxed Quickness, 50% perm buff, and 26% AS on staff.
If you are looking for fast way to farm some money - clear medals. Then make a boss run (start at wave 10), or pick Red Wings Natalie and graze 1k bullets. Kupo, please don't fix it, its the only reasonable way to get that last cheat upgrade :C
If you have problem with elevators - make it short! 5/6 floor elevators don't have queue! This need more $ and work, but you can use only basic and staff. And you can bulid more rooms, too.
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