Lost Kin

"Shattered corpse, reanimated by infected parasites. The shape of this creature... I have seen something like it before. More than once, perhaps. It looks a little like the bugs of Hallownest, but not quite the same. Where did these empty little wanderers come from?"

The Lost Kin is a hidden boss in Hollow Knight. It is the Dream variant of the Broken Vessel, faster and tougher than its physical counterpart.

Behaviour and Tactics
The Lost Kin shares its basic attacks with the Broken Vessel but attacks at a much faster pace. Notable changes are:
 * Aerial Slash: The Lost Kin falls much faster after finishing the slash.
 * Leap: The Lost Kin rises and falls much faster.
 * Cascade: The Lost Kin no longer uses this attack.
 * Slam: When the Lost Kin hits the ground, six blobs of infection now fly out as opposed to four.
 * Balloon: This attack now happens at much quicker intervals (2-3 seconds). There is a maximum of 6 balloons that can be alive at once and this attack only occurs after the Lost Kin has reached 1150 HP.

Dealing with the Infected Balloons can be the trickiest part of the fight as the rate they spawn can prevent healing. Unnecessary damage can also be taken when trying to dodge the Lost Kin's attacks and colliding with them.

The Defender's Crest Charm offers a damaging barrier around the Knight which defeats the Infected Baloons, providing ample time to heal. Other area of effect charms like Thorns of Agony and Spore Shroom can also be very useful to take out groups of Infected Balloons. Baldur Shell, when combined with Thorns of Agony, is also very helpful in this role. Shape of Unn combined with Quick Focus is useful for dodging the Infected Balloons. This approach can be more useful in the Pantheons, where the Lost Kin is not fought in isolation, as it is generally more useful against other bosses than Defender's Crest.

As with the Broken Vessel, it is recommended to stay low to the ground as the Lost Kin jumps around a lot. The only reason that would warrant jumping would be to avoid the Slash attack.

Like the Broken Vessel, the Lost Kin takes knockback from attacks. As such, Vengeful Spirit/Shade Soul is useful against it as well, especially when combined with Shaman Stone. Desolate Dive/Descending Dark is an all-around good spell to use in this fight thanks to its invincibility frames and range to clear Infected Balloons too. The constantly spawning Infected Balloons also allow for speedy acquisition of SOUL and extremely aggressive use of Spells given the limited chances to heal during the fight.

The Lost Kin also staggers very easily, meaning that using Quick Slash can easily knock it down and allow for a moment to heal.

If the Shade Cloak has been acquired, it is technically possible to dash through the Lost Kin's Slash attack. However, this is inconsistent as the Lost Kin is extremely fast and can sometimes perform the Slash attack before the Shade Cloak has time to recharge, additionally, if the dash is used too early or too late, it results in unnecessary damage. It is better to down strike the Lost Kin during the Slash attack instead, as this allows for more consistent damage.

Location
The Broken Vessel to be Dream Nailed can be found where it was first defeated, near the far left corner of the Ancient Basin, guarding the Monarch Wings upgrade.

Trivia

 * The Lost Kin, unlike other Dream Boss variants and Warrior Dreams, does not speak to the Knight upon defeat, but rather gives the option to "Accept", where it bows down at the Knight once before disappearing and giving Essence.
 * The arena where the Lost Kin is fought in Godhome is the same as the Broken Vessel's. The difference, however, is that the Infection's presence is replaced with vines and roots.

References

Fratello Perduto Zaginiony Krewniak Proche Disparu