I would take A synchronises ability that would allow me to duplicate another person's abilities and skill,not theirs knowledge, just powers and abilities of those nearby.
A manipulation of Astral dream energy onto the physical plane.
Omnimorphic ability to become any shape I wanted, including in between states, including chemical and complex mechanical movements.
My Item would be A vibranium/adamantium/uru alloy infused with cosmic energy to enhance its durability even further. In the form of armor.
Now as to what I'd do? Well, first I'd go meet as many superheros as I could, not for blackmail purposes but the let them know that they have a new ally. Then I'd probably go hang out with the X-men. . .