The zero loyalty ability allows you to draw a card, which means it really gains you a loyalty, and the -2 ability creates a 2/2 blue Spirit that gets a +1/+1 counter on it every time you draw a card
Even if Auto Tap is set to On, you can override it at any time in the game by entering Full Control (which you do by pressing Ctrl on desktop, or on mobile by tapping and holding your player avatar to enable or disable full control)
No sense in making you fix your mana before you can fix your mana, right
the second stage lets you pay two mana and tap it to create a 0/0 colorless Construct artifact creature that gets +1/+1 for each artifact you control
The Mayhem ability on Carnage does make him a bit awkward as a Commander himself, but he should excel in many different 99s
Youre also going to draw cards whenever anyone boardwipes, which means youll have an easier time rebuilding