Seems like a good ability until you look at Aerathi Berserk and see that it's a 2/4 creature for 5 mana thanks to rampage
While the card has become a sideboard staple of green decks throughout Modern, it has funnily enough made the most impact in Vintage, where its a great card against all the artifact decks while also providing Bazaar of Baghdad decks a reliable answer to Grafdiggers Cage and Leyline of the Void without requiring mana
If there is a creature you want that is in an opponents graveyard, you have the means to get that creature
I suppose you could go ham with this ability and just plan to spend all of your stones as fast as humanly possible, before you start losing Debt-ridden models
What many ignore is that if you only play constructed formats, buying and opening booster bought from the store packs is completely fine as this is the best way to earn Wildcards that can be exchanged for the exact cards you need to finish your deck
Then, we have Coppercoat Vanguard, which is highly aggressive and makes even your 1/1 tokens hard to deal with