What they are/What they look like
Constellation monsters are a type of monster appearing in StarlightSG's fanfiction, Yu-Gi-Oh! HYPERFORCE! They may also appear in Qwex67’s fanfic, Yu-Gi-Oh! Illusion, due to the fact that constellations don’t really exist and thus, when you see them, you’re seeing things that aren’t there, just like a… MIRAGE!!!
Constellation monsters have a background which represents outer space, more specifically a pattern representing circumpolar stars. Constellation monsters do not possess levels; instead they have "Star Clusters". They exist within the extra deck.
A Constellation Monster looks like this:
How to summon a Constellation Monster
Along with the Constellation Monster Type, there also exists Cometshower Spell/Trap types. These are depicted by an 8 pointed star next to their [Spell Card] or [Trap Card] definitions. Each time a player activates one of these cards, a player will gain/lose a set amount of Nebula Counters (the amount they gain will be specified on the card). To Constellation Summon a monster, a player must use monsters as Constellation Material, and remove an amount of Nebula Counters, equal to or more than the Star Clusters on the Constellation monster they wish to summon. Some Constellation Monsters have more than 1 monster tribute costs.
Constellation Spell/Trap cards
Constellation Spell/Trap cards are known as "Cometshower" Spell/Trap cards. They have an 8 pointed star as their icon, next to their [Spell Card] or [Trap Card] definitions. When activated, they will usually provide the player with Nebula Counters, although they can take some away from the player as a cost of activation or take them away from the opponent instead. They all state the following in the first two lines of the card's text:
This card is also treated as a *Spell/Trap kind* card.
To activate this card: gain/lose/opponent gains/opponent loses (0 to 12) Nebula Counters.
When a player activates a Constellation Spell/Trap card, and sometimes some Constellation Monster effects, they will gain a set amount of Nebula Counters. a player cannot have more that 12 Nebula Counters at one time, or less than 0 at one time, unless a card effect says otherwise. If they would go below 0 counters, they have 0. If they would go above 12, they have 12.
Astral Constellation Summon
What is Astral Constellation?
Astral Constellation is an evolved form of Constellation Summoning. It is used only for 'evolved' versions of Constellation Monsters. Naturally, they are stronger forms of them. They take some inspiration from Accel Synchro summons.
How to Astral Constellation Summon
To Astral Constellation Summon, you must use a specific Constellation Monster, and the Strength Classification of that monster must be higher than the monster listed in its summon condition. Just like regular Constellation Monsters, the amount of Nebula Counters needed equal the amount of Star Clusters the monster has.