boss of the gym скин майнкрафт
Boss Skin 1.2
Custom skin add-on for MythicMobs
If you liked the plugin please write a good review.
If you want you can also make a donation 
This plugin is an add-on for MythicMobs that allows you to use custom skins on your bosses ( you can also add items or armors ).
Both MythicMobs and Lib’sDisguises are required
Why use it:
With MythicMobs you can disguise your mobs only using existing player profiles, but with that plugin you are free to use every skin you want!
Current versions tested: 1.11.2, 1.12
(I have not tested it on previous versions of Spigot)
Setup:
First of all you have to upload the skin you want to use here and copy both texture value and texture signature fields.
Next you have to open you Lib’s Disguises folder(plugins/LibsDisguises/), edit the disguises.yml file and add a new line like here (I suggest to copy and edit the example line called libraryaddict, you can also modify or remove the disguise equipment)
You must use the internal name of your MythicMobs mob where underlined
Now replace the signature and value fields with the ones you have generated before
Then open the BossSkin folder (plugins/BossSkin/) and add the internal name of your mob in the list (remove the default name if present).
Finish! When you will spawn the boss it will use your custom skin!
I want to apologize if it is a bit tricky but I have developed it for my server and I never thought about publishing it.