While many of these passives can boost Kairos Fateweaver beyond any other spellcaster in all three Total War: Warhammer games, three of these passives should be highly sought after for players.
The second point in the Fragment's skill line will add that Lore of Magic's passive bonus to Kairos Fateweaver, regardless of whether Kairos has that fragment equipped. The first point in each of the Fragment skills will unlock an equipable item that will replace two spells from the Lore of Tzeentch with spells from that Fragment's associate Lore of Magic. While Kairos Fateweaver starts the game with access to the Lore of Tzeentch, his skill tree allows him to gain access to spells of other Lores of Magic starting at level 11. What makes Kairos Fateweaver different from the leaders of other factions in Total War: Warhammer 3 like the Lords of Kislev, is his spellcasting ability.