Just keep going at mobs or anything around your own level. Crates work the same way, however crates are 1 crate in an area (and switching channels takes time)
In the end its what you prefer... Switching channels and chopping the same crate over and over or killing a field of mobs over and over again. But the constant in this story is persistance, you just gotta keep going and going.
The more respawns, the more chances.
The stronger the mobs (super/ultra/boss), the higher the chances.
Kill more of a lower level, you get a lot more chances but lower chance per respawn.
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