@karserus: The site module is actually pretty good. Let's say you fired all your weapons at once and it did 20 damage total (you should be doing more by the time you get the site module). 25% more damage means you do an additional 5 damage, which is the equivalent of 5 weapons (or 2 weapons and a missile). So you're basically filling 5 spots on your ship in the space of one.
Easy way to farm coins: The first level for Lightning Girl's path (the first level to the right) has a turret. Use the turret to clear some enemies, hop out and collect the coins, then repeat. Immediately spend all your coins on the magnet. A few levels of the magnet, and you won't even need to leave the turret, all the enemies and coins will come to you. The level also seems to have lots of golden skulls, which are easy to completely kill with turret. A max level magnet can pull coins off screen, and will easily net 600+ coins on this level. Once it's maxed, level the amount of coin drops, which can easily bring your coin total to 1000 for the level (depending on the number of skulls you get).
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 "Super Villainy"){kind=icon}