The Ritual Dagger is one of the darker items added to PEAK in The Final Ascent update, and it does exactly what the name suggests: you stab a teammate in the back to fully restore your health. It also unlocks the Last Resort Badge, which requires you to pull off the sacrifice while sitting below 25% health. The catch is that none of this works unless you're in a co-op session with at least one other player.
Where to find the Ritual Dagger
The Ritual Dagger drops from Ancient Idols and Ancient Luggage. Neither has a fixed location, so you're working against random chance every run. Ancient Luggage appears more frequently in the later biomes, particularly GLOOM and THE CITADEL, so your odds improve the higher you climb.
One important restriction: the dagger will not spawn at all in solo sessions. If you load in alone, you can search every Ancient Idol on the mountain and come up empty, because the game simply won't generate it. You need at least one other player in your party for the item to appear.
PEAK Ritual Dagger Guide: How to Get the Last Resort Badge
How to use the Ritual Dagger to get the Last Resort Badge
Once the dagger is in your inventory, the process has two steps: get yourself low on health, then sacrifice a teammate.
Step 1: Drop your health below 25%
The Last Resort Badge specifically requires you to have 75% of your health missing when you use the dagger. The simplest way to hit that threshold is to find a drop and take fall damage until you're in the red. Don't use food or healing items after that, or you'll overshoot the requirement and have to damage yourself again.
Step 2: Sacrifice your teammate
With your health critical, get behind your teammate so their back is facing you. Hold Right-Click to perform the sacrifice. The dagger kills them instantly, turning them to stone (and occasionally shattering them entirely). In return, you receive a full health restore and every current ailment is cleared, including hunger, burning, and any other debuffs you're carrying.
The moment the sacrifice connects at the required health threshold, the Last Resort Badge unlocks.
Is the Ritual Dagger worth using outside of the badge?
Yes, in specific situations. If your entire team is starving and injured deep in a late biome, sacrificing one player so the survivor can reach the top and use an Ancient Idol to bring everyone back is a legitimate strategy. One person making it to the resurrection point beats the whole group wiping and losing the run.
That said, it costs a teammate their life, so communication matters. Make sure the person you're sacrificing knows what's happening and that an Ancient Idol is actually reachable. For a deeper look at all the ways to bring teammates back, check out the PEAK guide on reviving teammates before committing to this play.
What other badges can you unlock in The Final Ascent?
The Final Ascent added a full slate of new badges alongside the Ritual Dagger. If you're working through all of them, the PEAK all Final Ascent badges and cosmetic rewards guide covers every badge with exact completion steps and the cosmetic unlocks tied to each. The Exorcist Badge (burning the Big Ghost in GLOOM) and the Archery Badge (removing 10 arrows safely in THE CITADEL) are two others worth targeting in the same run if you're going for a badge sweep.
For everything else the game throws at you across both biomes, the full PEAK guides collection has you covered.