Living Brain, Mechanical Marvel

At the beginning of combat on your turn, switch the power and toughness of each of any number of target creatures until end of turn.

Equipped creature gets +4/+4.

: Until end of turn, this permanent becomes a 4/4 Spirit artifact creature that's no longer an Equipment. Activate only if you control no creatures.

Equip (: Attach to target creature you control. Equip only as a sorcery.)

Whenever Karn blocks or becomes blocked, it gets -4/+4 until end of turn.

: Target noncreature artifact becomes an artifact creature with power and toughness each equal to its mana value until end of turn.

: Another target Vehicle you control becomes an artifact creature until end of turn.

Crew 4 (Tap any number of creatures you control with total power 4 or more: This Vehicle becomes an artifact creature until end of turn.)

, : Until end of turn, target creature you control gains flying and has base toughness 1.

, : Target creature you control gets +2/+2 until end of turn. Return it to its owner's hand at the beginning of the next end step. (Return it only if it's on the battlefield.)