Little Catastrophe LV 3

[Lunar Origins]

Little Catastrophe LV 3
DARK / Level 3
[ Fiend / Effect ]
Cannot be Special Summoned by another effect monster's effect. When a monster is sent from the field to the Graveyard: You can send this card you control to the Graveyard; destroy 1 card on the field. When this card is sent from the field to the Graveyard: Special Summon 1 "Little Catastrophe LV 4" from your Deck.
[ ATK: 1000 / DEF: 2000 ]

Little Catastrophe LV 5
DARK | Level 5
[ Fiend / Effect ]
Cannot be Normal Summoned, unless by Tributing 1 "Catastrophe" monster. Can only be Special Summoned by a "Little Catastrophe" monster's effect. This monster's Summon conditions cannot be ignored. Your opponent can discard 1 card during their Standby Phase. If they do not: Destroy all Special Summoned monsters on their side of the field, and monsters cannot be Special Summoned until the End Phase. During the End Phase that a monster you control was sent to the Graveyard: Destroy all monsters on the field; Special Summon 1 "Little Catastrophe LV 8" from your Deck in face-up Defense Position.
[ ATK: 1900 / DEF: 2700 ]

Little Catastrophe Level 8
DARK | Level 8
[ Fiend / Effect ]
Cannot be Normal Summoned or Set. Cannot be Special Summoned except by the effect of a "Catastrophe" card. This card's Summon conditions cannot be ignored. This monster is not affected by the effects of other effect monsters. When a monster is Summoned: Destroy that monster, then inflict damage equal to its ATK to your opponent, and damage equal to its DEF to your own Life Points. During each of your End Phases: Special Summon 1 monster from your Graveyard.
[ ATK: 2000 / DEF: 4000 ]

[Zyzzyzus]

LV3 Summons LV4 rather than 5, when I think you meant 5.
The effect that Special Summons the next Level is a bit too broad with the requirements, I think. Rather than any instance of being sent to the Graveyard, I think it would be better if it only included being destroyed.