You can fight with boss every day only one time.
You cannot fight with boss even if you lose.
Any drop from boss have 3% chance, gold has 100% chance.

Bosses Name
Level
Exp
Event Points
Loot
Kuririn Defender
1-49
110.000
1
1x
Piccolo Defender
50-99
1 level
1
1-2x
Bardock Defender
100-199
1 level
2
1-5x
Freeza Defender
Cooler Defender
200-299
1 level
3
1-10x
C17 Defender
C18 Defender
300-399
1 level
4
1-10x
Cell Defender
Buu Defender
400-499
1 level
5
1-15x
Hit Defender
Janemba Defender
500-599
1 level
6
1-15x
Bebi Defender
Black Defender
600-699
1 level
7
1-15x
Gohan Defender
Trunks Defender
700-799
1 level
8
1-25x
Goku Defender
Vegeta Defender
800-899
1 level
9
1-25x
Jiren Defender
Brolly Defender
Beerus Defender
900+
1 level
10
1-25x