In my experience, it works essentially as Adventure from the Eldraine sets, as long as the creature has an enter the battlefield effect
You should pair it with haste enablers to mitigate the chance of this green creature dying before it exerts a creature into play
All you have to do is build up your energy counters and your artifact creatures can become deadly with first strike or trample
Rin and Seri, Inseparable can make especially good use of this effect, given that Mirror Entity counts as both a Dog and a Cat
As such, this style of discard cards tends to give the player more control of what gets discarded
Olivia, Crimson Bride Undead and loving it Olivia, Crimson Bride is the protagonist of Crimson Vow, resurrecting Edgar Markov in order to get married