Plane of Time Version: For event information, see this quest entry. Tallon Zek drops three items from his loot table.
Plane of Tactics Version: Max hit ~1,000; does not summon; shadowsteps himself around the room. Most of his damage output is from spells. Due to the "Tallon's Balance" debuff he casts, you will need to buff resists to ~450 before being able to resist many of his spell attacks.
Rathe Council Chambers Version: A chest with loot spawns after the Zek Brothers event.