Just a note but the silver you need to max the girl is 2800 not 5800 (500 x 3 for equip, 250 x 4 for skill and 300 for her).

To give an idea on rewards... lvl 77 boss gave 86 silver for a tap, not mine so don't know discovery but it's normally around 30% so around 28 would be right.

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Also the first boss you get for the event and INHO anything below lvl 40 just nuke yourself, people are not likely to help with a sub lvl 10 boss when so many high lvls are avaliable.