1) workshop upgrades multishot targets(7 lvl = free 100 waves), rapid fire and bounse amount are soo cheap.
2) darkness and nature are soo OP upgrades + shouldnt work on boss or weaken the effect of this upg on boss.
3) If you can achieve ~250 wave, then your start bonus will be too large, and you can upgrade all what you want to the max lvl.
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