Black Knife Simulator

Spoilers

The sword and the song

Back in Chapter 2, Queen's light show drives a blade into the earth. Her line is that the Knight sent its will through that blade and raised the fountain from the ground. Chapter 3 is the fight where the weapon is finally visible. The box-splitting swing and the spinning cuts are strokes of it. During the tunnel, the steel itself is the bullet and it travels on a red aim line.

Force the win and the shape stutters. Susie's swing only chips the steel. Black fills the screen, Susie and Ralsei drop swooned, and the notched blade puts Kris on a knee. The cutscene after the chip flies is still a loss for the party. On the grab after that, Undyne intervenes and she is the one taken away.

That chip is equippable. The check says "A dagger-like shard of the Black Knife. Strikes the weakness of dark-element enemies." Attack rises by 16, with SlayDark, and Kris can wear it. Outside the Dark World it checks as a small chip of extremely hard glass that is nearly opaque, and both the name and the attack stat survive the trip. Its slash animation is red and black, in the family of the spinning cut. Titan Spawn suffer tenfold damage from it. A shielded Titan takes triple damage, and an unshielded Titan takes tenfold, where other swords deal half and fivefold. Those multipliers stand in for a dark element the game never actually implements.

In Chapter 5, Ralsei reads a document Asgore wrote a day earlier. It locates black shards at a Dark World from long ago and at the library after the Cyber World was sealed. Susie takes that to mean the Knight made both places.

One prophecy couplet names the weapon outright: "THE KNIGHT WHICH MAKES WITH BLACKENED KNIFE. SHALL DUEL WITH HEROES STRIFE BY STRIFE."

Spoilers

Dodging the blade, phase by phase

Same keys as the number menu promised: arrows or WASD, Z or Enter, X or slash to slow the heart, C to rush speech. The sword is the single-edged black blade. Box splitter and the rotating cuts are swings of it. In the tunnel, the steel itself is the bullet.

• The fight cycles stars, tracking swords, the splitting cut, the tunnel, and the spinning slash. That loop's third pass continues until HP is below four fifths. Then a late spinning cut, a charge you can heal through, and the screen-wide roar.
• Stars: take a wide gap. Early on you may stand still. The white beams are the shard map. The hitbox is the center dot. Later shards turn red and chase one by one.
• Swords that track you go red, pause, and cut, in the order they showed up. A diagonal blade still loses to a straight step if you are not crowding it.
• The splitting cut shoves the board apart and sprays diamonds. It takes about two thirds of a full bar, one third if the mantle is on, and it stops at 1 HP. Near a corner is calmer than inside the corner. Grazing the cleave beats grazing the diamonds for TP.
• The tunnel has almost no mercy frames. Follow the empty lane, on the right, with small steps. Red lines mark the last crossing. One pass rotates counter-clockwise. Another squeezes the lane.
• Spinning lines start from the spot you occupied when they appeared. Pick a direction, then correct late, and drift back to the middle before the spiral.
• During the roar the board is the whole screen. Stars leave, return, and burst. The last slash is down the center. Armor and DEFEND are ignored. The line about the foe dropping its guard is the window that actually ends it.