If you plan on going super wide with Slivers, especially with cards like Sliver Queen that produce a lot of tokens, this is a solid addition
Your other option is also excellent, which is to fight with one of your opponent's creatures, which is one the 7/7 monsters will almost always win
I cant fault you for picking up a playset at prerelease weekend so long as you can get them for $3
The Golgari side sacrifices a dork you control to recur one card per color from your graveyard to your hand
Since you can repeatedly cast it from your graveyard at the small cost of just two life, Tenacious Underdog is a reliable creature and draw engine for multiple decks in Standard
Whether you need Treasure tokens for ramp or to funnel them into cats and dogs with Jinnie Fay, Jetmir's Second, Smothering Tithe can generate so much value in a 4-player pod