Can someone create a base system for me so i can understand it and work off it?

What i was thinking is that you collect 10 Golden Key's from boss drops, When you have all 10. You use it to challenge the Boss Leader which will drop different things. The more keys you get the better boss you can challenge who s' drop rate is better.

Here is my layout:

10 Keys - easy boss - 5% (1 try, if u die u are out of the area moved back to home)
30 Keys - medium boss 20% (1 try)
70 Keys - hard boss - 50% (2 trys)
100 Keys -super boss - 60% (3 trys)