It is a threat in its own right and it is a combo piece but also just a very good card
A further consideration for Buried Ruin is in colorless decks
I maintain two saved eBay searches for Magic cards: one for Alpha cards sold by ABUGames at auction, and the other for Beta cards from the same seller
Mega Starmie exs damage-spreading capabilities are especially popular in tournaments, Mega Zygarde ex has a ton of Fighting-type support, Mega Dragonite ex boasts one of the most powerful attacks in the game, and Mega Skarmory ex can threaten key support Pokmon, such as Meowth ex
To exploit those strategies, you need to fill your graveyard, and Golgari Grave-Troll is one of the best ways to do so
Tips: For improved clarity of the game state (life totals and commander damage especially) use Lifetap or a similar life counter app on a smartphone when playing Breena