Which part of the project is this related to?
Survival
Detailed description of the idea (1 idea - 1 post)
The task "kill 20 vindicators" is almost impossible because they can only be found in Woodland mansions, which are rare and hard to locate in a limited-size Survival world (there aren't even maps to search for mansions). Instead, I would suggest tasks like "Have 10 dragon heads" or "Kill 1 Warden".
To which server do you want to receive the reward?
Survival