The Legion’s resident guerilla warfare hater, Tybalt Marr is a true son, which refers to a genetic defect which makes him resemble Horus Lupercal, their gene-father closely, this is how he got the nickname “The Either” as his close friend, Verulam Moy and him looked so similar and behaved so similarly they might as well been twins, hence the nickname for Marr “The Either” and Moy “The Or”. Moy would be killed during the conquest of Davin and Marr would fall into grief, isolating himself until the eve of the Horus Heresy where Horus Lupercal would personally induct him into a warrior lodge, securing his loyalty to the traitor cause and leading to him fighting in the dropsite masacre where he would fight Shadrak Medusan and his adhoc army known as the shattered legion, an army made up of Iron Hands, Raven Guard and Salamander legion survivors who would stage guerilla warfare. This would encourage Marr to devote himself to wiping out these survivors, and with the blessing of the warmaster Horus and a gift of a new sword called the culling blade he would go on to slay shadrak and dismantle shattered legion operations throughout the dark empire of horus.
He would meet his end during the saturnine gambit when he was ambushed by Garviel Loken, The black shield group known as the Fangs of The Emperor along with the imperial fists and blood angels. Marr would be slain along with most of his company in the initial ambush as he left this terrax drill and Loken shot him clean in the head with a bolter, killing him instantly before he could even put on his helmet.

In game, like most his brothers Tybalt is a high command choice costing 140 points, he has normal Praetor stats but one less wound for some reason, probably because he is technically a slightly lower rank as last edition he was a centurion. He comes with hatred (shattered legions), probably from the time he along with Horus Lupercal almost got assassinated via strafing run by a shattered legion cell, other than that his only unique thing is the culling blade a S user, Ap3 damage 1 sword with poisoned 2+, breaching 5+ and critical hit 6+, its okay? poisoned 2+ is neat for fighting things like solar auxilia ogryns or mechanicum tech priests who have an abnormal toughness, but the Ap3 will let you down against 2+ save targets, thankfully breaching 5+ means it can become Ap2 on a 5+ to wound and critical 6+ means a 6 to hit will be damage 2 Ap2 but in my opinion he is too swingy for my taste and that one less wound means a saturnine hammer, saturnine fist or a regular power fist or thunder hammer can achieve a one hit kill on him in a challenge. Its also slightly funny he can not actually use his hatred for the shattered legions in melee as poisoned 2+ means he will always wound on a 2+ anyways.
In terms of books he appears briefly in Horus rising, and frequently throughout the shattered legion series as the main villain of the series. Anyone who has read the shattered legion series will probably sigh and get flashbacks to the war when they are mentioned as they are an often maligned series for having plot holes big enough to float a boat through, cheesy writing and introduced a character so edgy and overpowered a large chunk of the player base refuses to acknowledge his existence. Give the first one a read and make up your mind from there would be my suggestion.

His miniature is solid overall, A popular model to use to convert other characters off of as he is one of few new scaled characters in MK4 armor, Ironically I’ve probably seen his miniature be used as a base for other characters more often than Tybalt mar himself, a common one being for Loken or for the ultramarines character Aeonid Thiel