Much like Chara, Soulless Kris has the ability to give a single Artifact: Outbreak. This Artifact summons a Soul Cage at the start of every even turn. However, unlike Chara, Soulless Kris gives this Artifact to the opponent.
This is because Soul Cages are a death sentence. If you have 4 of them that die during the opponent's turn, you lose the game. As such, as the user of Soulless Kris, you want to make sure you have the cards needed to kill it. This is easier done in Justice due to its damaging spells and passive effect. Keep in mind that Perseverance isn't as easy, as KR is triggered at the start of the opponent's turn rathan than at the end of yours. This means that Soul Cages that die from KR won't trigger their Dust.
Soulless Kris also summons a Soul Cage for the opponent right away and has Haste, so it's able to deal 4 of the 5 DMG needed to kill it. This is where Justice's passive comes in play. If Soul Cage is by itself, the passive will simply finish it off. Other souls need another card to get rid of it.
When you receive the Outbreak Artifact, remember when one will be summoned, and prepare accordingly. Like Soulless Kris, it also has Haste, so it's able to attack right away. You want to attack an enemy monster with high ATK in order to let it die right away and avoid its Dust, otherwise you will need to use up other recourses. The enemy can also make it difficult by using low ATK Taunts, though.