Activate Ruthless Knave's first ability by paying ({2} magic symbol) ({B} magic symbol) and sacrificing a creature, creating four Treasure tokens and four 1/1 Squirrel creature tokens.
Activate three Treasure tokens by tapping and sacrificing them, adding ({2} magic symbol) ({B} magic symbol) .
Repeat.
Once you have infinite Treasure tokens, you may use them to activate Ruthless Knave's second ability.