Varro Tigurius
Varro Tigurius is one of the most powerful loyal human psyker currently alive. And he belongs to the Ultramarines. Who would have thought? He is so powerful he can beat daemons like a Grey Knight, he can fight like a Terminator, use every known psychic power (and several unknown ones) AND foresee the Hive Mind's plans. Somehow. It is worthy to note this is the same Hive Mind that blots out a psychic power on par with the God-Emperor of Mankind Himself. How one man can use the warp against this is unknown.
In spite of all this, the Daemonculaba still gives him nightmares.
Also did we mention this was BEFORE Matt Ward wrote him? Except he was Ld9 because due to his awesome powers his soul just shine in the Warp like a giant neon banner with a sign "eat me daemons, I'm so delicious!" on it.
Tabletop
In game, he's one of the best psychic characters available, being ML3 and has the in-built ability to re-roll his selection of psychic powers if you didn't like any of them the first time and his prescience ability allows his detachment to re-roll for reserves (pass or fail). These alone would qualify him as a high tier character.
But not only that, his wargear helps him out significantly too, with his Hood of Hellfire granting him the ability to re-roll failed psychic tests, which is amazingly potent. It can encourage you to use less warp charges in a given casting since you get a second chance to succeed, therefore providing you more powers later in the phase.
His other unique item is his Rod of Tigurius which is a master-crafted Force Staff That was held by Malcador in the Great Crusade with the Soul Blaze rule, so not really much to shout home about, but notable nonetheless.
On the flip-side to this mental might, his statline is not the great as some of the other main Chief Librarian characters out there like Mephiston, Ezekiel or Njal Stormcaller and he's the only one of them who doesn't have a 2+ Armour save or some form of Invulnerable save, so he's comparatively fragile.
See Also
- Illiyan Nastase - The Rogue Trader-era Chief Librarian of the Ultramarines, people occasionally confuse Tigurius for this guy