mm deserves to be killable as easy as its easy to play.
This build lives too long, there is not big difference between good and bad mm. In both situations its extremely annoying and impossible to play against - he just stands on the node, tanking with his face everything. Even bad mm lives long enough to have +1 that means a loss of the node.
U can kill scourge +/- fast, u can kill fast a reaper, but not core build. He has huge shroud hp that gives an ability to soak lots of damage, i has a decent dmg, so he wins every hp tradeoff even being 1v2. Minions give tons of toughness so mm doent care of any damage type - he is good in condi cleanse, and has enough toughness to ignore power damage.
Existing a mm in opposite team leads to gameplan change, just realize - existing only one char forces u to change all gameplan if u want to win, despite u have good setup for teamfights, just because mm lives long enough to have +1 for the help.
So this class has rly too much, and sould be tuned down