Amusingly, Althran's force was included as the first
Elf Aelf Warscroll for Age of Sigmar although his Gryphon model was no longer available, and not long after his footplodder model was also moved to Last Chance and sold out along with most of the other Order models on 3/25/16. Games Workshop rereleased him along with the rest of the Island of Blood set in December 2016 under the new name Spire of Dawn.
Althran's lineage is extremely prestigious, going back to the time of Aenarion as the leaders of the Phoenix King's armies both in Ulthuan and abroad. Between honoring his family legacy, typical High Elf skill and arrogance, and his fucking amazing magic hand-me-downs he's the posterboy for High Elf characters who aren't important enough to deserve their own rules.
He comes equipped with the Armor of Fortune, technically Heavy Armor but fitted to him to allow all natural range of movement unhindered. His Gryphon's name is Sharpclaw and he prefers to swoop into battle shouting commands from its back.
Althran met a Wizard named Caladris during the Battle For Stormkeep (of which there is no lore except a mention) when the latter used fire magic to save the former from Trolls that had surrounded him and the two have been friends and companions (perhaps in the...Greek sense?) ever since.
When the Island of Blood was assaulted by Skaven lead by Skreet Verminkin, Althran answered the call for aid to the mainland. After narrowly defeating the Skaven and sending them fleeing back to their holes his army was joined by a much larger force lead by Tyrion for the counter-attack. Said counter-attack has no lore because its just a plot-hook for Island of Blood purchasers who expanded their force, but at the very least Tyrion survived.
On The Tabletop
Althran has two models. The first is the one on a Gryphon found exclusively in the Island of Blood set, usually used by players as a generic Prince. The other is Althran on foot, used as an alternative Noble or Prince.