Sacrifice can rescue a dangerous turn, but its Block is only one side of the exchange. Osty must be alive, and using the card kills him. A strong calculation includes what the rest of your hand can still do afterward.
The beta calculation
The v0.110 notes increased Sacrifice's Block from double to triple Osty's Max HP. The inspected v0.111 notes contain no further Sacrifice change.
For an illustrative Osty with 10 Max HP, the beta card's printed calculation gives 30 Block before other effects. If he has only 2 HP remaining, the input is still 10 Max HP. Current HP and Max HP are different values.
Our Sacrifice reference contains the stored main-branch description. This guide uses the beta multiplier; do not mix the two in a combat calculation.
Compare the whole defensive turn
First read the incoming attacks. Then work out the Block from Sacrifice and from any other cards you can afford. Check whether that total covers the actual turn, including effects that alter Block or damage.
Next consider the line where you keep Osty alive. Does another defensive card already make the turn safe? Does removing him interrupt an attack sequence or a plan for the following turn? A larger Block number is not automatically a better complete turn.
Avoid counting Osty's remaining HP as if it were ordinary Block without checking the game's current targeting and damage interactions. This guide supplies the Sacrifice calculation, not a universal damage-allocation simulator.
Sequence cards that need Osty first
Read the requirements of the rest of your hand before playing Sacrifice. If another card needs Osty alive, killing him first may remove that option. Reordering the same hand can be more important than adding another defensive card to the deck.
That does not mean Sacrifice always belongs last. Effects in a particular fight may make another order preferable. The safe habit is to identify dependencies before committing a card, then verify the resulting state after each action.
When the card belongs in your deck
Sacrifice is appealing when you already build Osty's Max HP and need a large answer to occasional dangerous turns. It asks more of a deck whose plan cannot easily function after Osty's death.
Consider how you will rebuild afterward using the cards and resources actually available. If the fight continues for several turns, surviving this attack is the beginning of the recovery plan. If the card helps you reach a confirmed lethal turn, losing Osty may matter much less.
The Osty and Doom A10 guide covers the broader character plan. Shroud and Time's Up offer a separate look at the newest Necrobinder adjustments.
A useful post-run check
Find a turn where Sacrifice was either excellent or disappointing. Record Osty's Max HP, the incoming damage, what else was in hand, and what happened on the next turn. Those details tell you whether the deck needed the card, more preparation for it, or a different defensive answer.