In this case, you just get a mana dork ability
For starters, it's quite hard for opponents to get rid of Sensei's Divining Top once you play it, given its built-in tuck myself into the library ability
Vren, the Relentless Vren, the Relentless provides an intriguing twist to rat decks
Illustrated by Joe Slucher Standard Not Legal Alchemy Not Legal Pioneer Not Legal Historic Not Legal Modern Legal Brawl Not Legal Legacy Legal Comp
For example, if you cast Flametongue Kavu, deal damage with its enters-the-battlefield ability, exile and return it to the battlefield with Momentary Blink, deal damage again, then cast Momentary Blink with flashback on Flametongue Kavu to repeat the process one more time, you've fulfilled Case of the Burning Masks's "to solve" trigger condition
The alternative-art Penny is one such specimen