If a character with Mastermind takes, say 5 damage, and has a pog sitting next to him, can he give all 5 clicks to the pog? I assume yes, but wanted to find out while I am working on a team build.

Yes you can. You transfer all damage at once. It's like hitting a piece for 5 damage on his last click. One damage was enough to kill him, but he would take all 5.

-Immortal_Raven

Thanks much!