Deal three damage to each of three opponents, then begin your postcombat main phase with Neheb, the Eternal in play: that nine life lost becomes nine red mana. Neheb rewards damage spread across the table, making small multiplayer burn effects into fuel for a much larger second half of the turn.
The count includes life opponents lost for any reason during the turn, not just damage from Neheb or from sources you control. Combat, a burn spell, and an opponent's life payment can all contribute. His afflict ability even makes blocking him costly: becoming blocked causes the defending player to lose three life, which can feed the later mana trigger.
Purphoros, God of the Forge offers a productive partnership. Creature entries damage every opponent before Neheb converts the combined life loss into mana. You can use that mana to cast more creatures, pay for an expensive Dragon, or launch a large Comet Storm. The timing creates a natural sequence: establish damage first, then spend the resulting mana after combat.
Aggravated Assault adds another route. Its extra combat is followed by another main phase, giving Neheb another postcombat main phase in which to trigger. If enough life has been lost and the setup remains intact, his mana can finance repeated Assault activations. You do not need fresh damage in every combat for earlier life loss that turn to remain part of the count.
Neheb is especially useful when your deck already wants table-wide damage. Keep some plays affordable without his trigger, though: removing him before the postcombat main phase can leave an ambitious hand waiting for mana that never arrives.
