In 2005, Magic would make its first visit to the plane of Ravnica, a massive city governed by ten guild that would go on to become the game's most popular and iconic setting. For the first Ravnica block, Magic designers created a new keyword mechanic for the ten guilds, each matching the flavor and personalities of the guild. The Gruul are based in Red and Green and are responsible for protecting the remaining wild areas of the city, being closely connected with the natural world but also rowdy and impulsive. Their mechanic, Bloodthirst, perfectly encapsulates this wild side and penchant for violence in both name and function.

Bloodthirst is an aggressive keyword that rewards you for being patient when deploying your threats. Essentially, it makes your creatures bigger if an opponent was dealt damage earlier during the same turn. It must be damage though, so cards that cause your opponents to lose life like Exsanguinate won't cause it to trigger. However, it doesn't specify combat damage or require that damage to be done by you, so pinging an opponent with a Spear Spewer or waiting for them to tap their City of Brass during your turn will enable Bloodthirst. Once an opponent has taken damage, your creatures with Bloodthirst will enter the battlefield with additional +1/+1 counters equal to the Bloodthirst number, which can range from one to six or even, on occasion, the total amount of damage dealt. The mechanic is simple to enable and easy to understand, making it a perfect fit for the player that just cares about having the biggest monsters.

After the mechanic's first printing in 2006's Guildpact, it would return a few years later in Core Set 2012. While it was only printed on Red and Green cards during its first outing, this second appearance saw it expand its color identity into Black as well. This would be the mechanic's last appearance for more than a decade. While it has yet to appear as a core mechanic in another main set, we did see two one-off cards with the mechanic recently: Indoraptor, the Perfect Hybrid from Universes Beyond: Jurassic Park and Twins of Discord from Modern Horizons 3 Commander. Indoraptor is the first and only legendary creature with this keyword and has a color identity that allows you to play every Bloodthirst card, making it a great Commander for a Bloodthirst-matters deck. Twins of Discord, on the other hand, is a colorless Eldrazi that grants your other colorless creature Bloodthirst 2, restricting its use to colorless decks and artifact creature decks.

Unfortunately, while Bloodthirst has a lot of potential mechanically and flavorfully, it never really left any lasting impact on Magic. There are only 24 cards in all of Magic with the keyword, and many of them are draft commons and uncommons that don't have much else going for them other than the chance to get bigger. The mechanic has not seen any significant play in competitive 1v1 formats, and unless new Bloodthirst cards are printed it will likely never show up in a tournament setting.

According to EDHREC, the most popular Bloodthirst cards in Commander are Twins of Discord, Indoraptor and Bloodlord of Vaasgoth, a vampire with Bloodthirst 3 that also gives your other vampires Bloodthirst 3. This card is my personal favorite card with Bloodthirst; not only is it an incredible flavor win that showcases vampires' literal thirst for blood, but it's also a great vampire lord that lets your vampires keep their stat buffs even when it leaves play. Cards like this show off the mechanic's potential, and I personally hope we see the mechanic explored further in a future main set.

That's about it for Bloodthirst, so I'll wrap up this Mechanics Overview here. If you want to learn more about the mechanic, check out this article, which includes a deck list for Indoraptor and shows it off in a game of Commander.