Teysa Karlov gives black-white aristocrats decks more value from the deaths they already arrange. When a creature dying causes a triggered ability of your permanent to trigger, it triggers an additional time. Blood Artist, Zulaport Cutthroat, and other death payoffs can therefore produce more pressure from each sacrifice without requiring a second creature to die.
She also gives your creature tokens vigilance and lifelink. That makes the token army useful beyond sacrifice: it can attack while remaining available to block, and combat damage can restore life spent on other effects. Elenda, the Dusk Rose benefits from additional relevant death triggers and leaves tokens that appreciate Teysa's combat abilities.
The wording is about triggered abilities caused by creatures dying. It does not double every sacrifice payoff, and a token-creation replacement effect is a different kind of ability. A creature exiled instead of dying does not create a death event for Teysa to amplify. She also does not provide a sacrifice outlet herself, so the deck still needs ways to control timing and a supply of creatures worth spending. Build the engine in those separate roles: bodies, outlets, and payoffs. Teysa makes the payoff stage stronger while helping surviving tokens contribute to combat, giving the deck a useful alternate plan when graveyard interaction or removal interrupts the main sacrifice sequence.
