An'ggrath

Overflowing with piss and vinegar.

An'ggrath the Unbound, the Guardian of the Throne of Skulls, Most Favoured of Khorne, Lord of Bloodthirsters and the Deathbringer is the most powerful of Khorne's greater daemons and should by rights then be a hard as bastard who would reduce neckbeards to manly tears and gnashing teeth of jealously at his bad-assness.

Instead he is an hilarious example of fail as each of the times he has been mentioned he has been soundly beaten and sent running back to his master with his tail between his legs. Perhaps he represents the concept of loss in war? No idea but it would go a way to explain why he sucks at winning.

During the Horus Heresy, Lorgar, weakest of the Primarchs, had to face An'ggrath, in a duel to prove his loyalty to the Chaos Gods. You'd expect Lorgar, who got kicked about by his brothers, to be well and truly curb stomped here but no, he gave An'ggrath a well resounding butt kicking instead. Did my cup of tea just fall from my hand in surprise? I think it bloody well did.

The first time he was summoned into the material plane was on the hive world of Ashur where Khornite cults were being purged by the Metamarines chapter. In desperation they invoked An'ggrath's name and summoned him, where he proceeded to BUTCHER EVERY LIVING THING ON THE PLANET. It took him 7 years to do so, which some would think is too long for such an angry winged tower of strength and savagery with an axe and whip, but consider that that he has to chop his way through entire hive cities worth of guardsmen and gangers, as well as an entire chapter of space marines.. Add in that he has to fly from hive to hive, and it could very well take him those 7 years, after which he just disappears. Therefore he was not defeated and banished back into the warp, but simply ran out of things to chop apart.

The second time was during the siege of Vraks. Towards the end of the conflict An'ggrath finally decided to show his face, perhaps hoping to steal some of the glory while noone was watching. Unfortunately for him the Inquisition got a whiff he was creeping around and one of their Inquisitors, armed with a potent toothpick, promptly pricked An'ggrath and sent him yelping back to Khorne's throne (although to be fair the toothpick was made specifically to kill ultra daemons so that helped Inquisitor Hector Rex cut off An'ggraths knackers).

The Blood God did sigh and put his head in his hands, shaking it with despair. What is an evil god to do when the best he had is something that cannot even take out one, unaugmented, unsupported inquisitor?

Well, call Forge World of course! Thus they made a model (though good ol' GW has made a cooler one) and rules for him. To be honest he just looks like a normal bloodthrister pumped full of steroids. Don't do drugs kids! You'll end up all red, veiny and unable to do anything but RAAAGGGEEEEEEE. At 888 points of gargantuan creature rules, only Angron and some of the bigger Titans have a chance of taking him on face to face. Hence, there's a bit of dissonance between the crunch and the fluff regarding An'ggrath: specifically, it is impossible for most of the characters that do beat him in the fluff to actually beat him. Crunch-wise, he's practically unbeatable in a one-on-one scenario, except in shooting contests with titans, of course (teh cowards, teh fewls, PUT DEM GUNS AWAY an do sum propa fightin).

Canon is shifty on whether Ka'Bandha or An'ggrath is in fact the most powerful Bloodthirster, as multiple conflicting sources and titles each state that one or the other is in fact more full of RIP AND TEAR.