So the Bloodthirst mechanic is definitely coming to the new Core Set.
Time to talk critically about it, yet?
One direction bloodthirst development was well explored in Ravnica block was making your vanilla creatures bigger. The "Gruul" clan, represented by the red/green color combination, were all beserkers anyway so bigger beatsticks usually suited them well.
A few of them were more tricksy. Burning-Tree Bloodscale was surprisingly powerful, getting bigger while using a powerful reverse-imp ability to get rid of weaker utility creatures.
Few of the original Gruul cards would be what you would call "clever" cards. Now that the Core Set will be presenting Bloodthirst from a non-Gruul perspective, I'm hoping to see two exciting innovations.
1) Bloodthirst in colors other than red and green. Can all colors be made to fit the battle-hungry "bloodthirst" mechanic? I personally think so. Definitely in white, black or green. Blue? Typically not hungry for battle…unless they make a cycle!
2) Bloodthirst abilities that do things other than make a creature better in combat.
The heart of Bloodthirst is putting +1/+1 counters on your creatures. You do that by causing damage, usually by attacking. If you are attacking, you must already be doing ok in the creature department, being either faster, bigger or smarter than your non-blocking opponent. Particularly if they know you are running Bloodthirst in your deck.
Getting a bigger creature after you already successfully attacked is somewhat like giving the mouse a cookie because he doesn't have anything to go with his milk. He gets his cookie, but only through a weird and unnatural progression of events.
What I want to see more of are cards similar to the often neglected Skarrgan Skybreaker.
I've been trying to build decks out of him for a long, long time.
Not only do you get a big creature, you also get a powerful board-wiping ability. Smash in with the Skybreaker, and if things get crazy you can always blow up the board and start over with some more creatures (hopefully with bloodthirst enabled!).
I even had a combo worked up using Deathrender where I could kill my current creature, play a Skybreaker for free, and then blow him up to clear the board.
My problem, eventually, was the cost and the inconvenience. Compare Skybreaker with the more commonly found Bloodfire Colossus.
With the Skybreaker you are paying one less mana stretched across two different colors. And you have to enable Bloodthirst to get maximum value out of the Skybreaker!
Or, for 7 mana in Red you can just cast a helpful instant called Inferno which we've had since The Dark.
One of my favorite red cards from recent sets was Ashling the Pilgrim. Gets bigger and bigger, can eventually be exploded into a sweeper. 2 to cast, ability is a further 2. That's how we should be doing Bloodthirst, Wizards.
And while we are on it, let's do something like Bloodhusk Ritualist. Only instead of multikicker, he would have Bloodthirst. Now that's card advantage! I already have the deck to put it in.