Does Defy work on Death from Below if I spend multiple power?

Yes, Defy can work on Death from Below, regardless of how much power is spent on it.

Why this works

According to RiftJudge FAQ #3777 and #7464, effects that check a card's cost (like Defy) always look at the printed cost in the upper-left corner of the card. They do not consider any additional costs, discounts, or variable power amounts paid during resolution.

• Because the printed cost of Death from Below meets the requirements for Defy (which targets spells with no more than 4 energy and 1 power), it is a valid target.
• Any additional power spent or any other modifications to the cost do not change the card's printed cost, so they do not affect whether Defy can target it.

Timing and Sequence

For Defy to successfully counter Death from Below, it must be played while the spell is on the chain, before it resolves.

1. Opponent plays Death from Below: They place it on the chain and choose a target. The game state becomes CLOSED.
2. Response Window: You have the opportunity to play Defy as a reaction to Death from Below being played.
3. Resolution:
   • If you play Defy, it is added to the chain on top of Death from Below.
   • Defy resolves first, countering Death from Below.
   • Death from Below is removed from the chain and does not resolve; therefore, its effect never happens.

If you wait until the opponent has already begun resolving the spell or paying costs associated with its effects, it is too late to use Defy.

Note: I could not fully verify this ruling against the retrieved rules.