This blogpost refers to the “Back in Action” Trickdraw card. You may have received it by backing the Trickdraw Kickstarter, by requesting it to be used with a Promotional Edition, or by some other top secret means. “Back in Action” is not part of the base game. Its use is entirely optional.
This is the first card in Trickdraw to interact with the discard pile. As such, it is important when playing with this card to keep the discard pile tidy, and to stay mindful of which card is on top. This is not necessary for normal Trickdraw gameplay (but still recommended).