A cool plot might be that a powerful goblin shaman in the Goblin Slayer world discovers a way to open portals to other dimensions and accidentally connects to the Destiny universe. This leads to a flood of goblins invading certain areas in Destiny. The Vanguard in Destiny then seeks the help of the Goblin Slayer to close the portals and defeat the goblins. The two groups would have to learn from each other's combat and strategic styles to succeed.
Perhaps the Goblin Slayer is somehow transported to the Destiny universe. He then has to learn how to adapt to the new environment and technology. He could join forces with the Guardians to fight the various alien threats in Destiny. His goblin - slaying skills could prove useful in dealing with smaller, more agile enemies that the Guardians sometimes struggle with.
One possible plot could be that the Guardians from Destiny are called to the world of Goblin Slayer due to some strange energy anomaly. They team up with the Goblin Slayer to fight against an army of goblins that have been enhanced by a Darkness - like power. The Guardians' advanced technology and powers would make for an interesting contrast with the more medieval - style combat of the Goblin Slayer.
Obviously, the Goblin Slayer himself would be one of the main characters. From Destiny, the Guardian, especially a Hunter with their stealth and agility, could be a great match. The Hunter's ability to quickly dispatch enemies and traverse difficult terrain could complement the Goblin Slayer's more brute - force approach when it comes to goblin - slaying.
One possible plot could be that the Doom Slayer is somehow transported to the world of Goblin Slayer. He then teams up with Goblin Slayer to take on an especially powerful horde of goblins that have been corrupted by demonic forces from Doom. Their combined skills in combat, the Doom Slayer's superhuman strength and arsenal, and Goblin Slayer's knowledge of goblin tactics would make for an epic battle.
One possible plot could be that the female knight from the 'Goblin Slayer' world gets transported to the 'Naruto' universe. She teams up with Naruto and his friends to fight against a new threat that is a combination of goblins and some of the villains from the 'Naruto' world, like Orochimaru who has somehow managed to use goblin - like creatures in his experiments.
For a Goblin Slayer crossover fanfiction, consider a crossover with 'Harry Potter'. The Goblin Slayer could be transported to the wizarding world. He would be confused by the magic there at first, but then realize that goblins also exist in this world. He could team up with Harry and his friends to stop a goblin - related dark magic plot. This would bring a unique mix of the gritty, down - to - earth fighting style of the Goblin Slayer with the magical world of 'Harry Potter'.
How about a crossover with 'Fairy Tail'? The Goblin Slayer's serious and methodical approach to slaying goblins could contrast with the more flamboyant and magic - using mages of Fairy Tail. They could team up to fight goblins that have been magically enhanced or are causing trouble in the Fairy Tail world.
One possible plot could be that the Doom Slayer somehow gets transported to the world of Goblin Slayer. He then uses his advanced weaponry and combat skills to help the Goblin Slayer in his never - ending fight against the goblins. Maybe they team up to take on a super - powerful goblin boss that neither could defeat alone.
There could be a cultural clash. The Doom Slayer comes from a more futuristic and hellish setting, while the Goblin Slayer is in a medieval - ish fantasy world. Their ways of communicating and understanding the world are different. However, this could also lead to some interesting exchanges. For example, the Goblin Slayer might be fascinated by the Doom Slayer's energy - based weapons, and the Doom Slayer could be intrigued by the magic and alchemy in the Goblin Slayer's world.
One interesting aspect could be the contrast in their fighting styles. The Goblin Slayer is more methodical and strategic when dealing with goblins, using his knowledge of their habits. The Doom Slayer, on the other hand, is a force of pure destruction. In a crossover, perhaps they could learn from each other. The Goblin Slayer could pick up some of the Doom Slayer's more aggressive tactics, while the Doom Slayer might gain some strategic thinking from the Goblin Slayer.
One possible plot could be that Naruto and his friends from the Naruto universe are suddenly transported to the Destiny universe. They could be mistaken for new Guardians at the Tower. Naruto's chakra abilities might be misinterpreted as a new form of Light power. They then have to team up with Destiny's Guardians to fight against a common enemy that threatens both universes, like a powerful Darkness entity that has somehow found a way to cross over from Naruto's world where the Akatsuki's actions have weakened the barriers between worlds.
One idea could be that the Goblin Slayer gradually gains the affection of various female characters as they see his unwavering dedication to slaying goblins. For example, a priestess might develop deeper feelings as she witnesses his selfless protection of the village. Another could be a female warrior joining his cause and falling for his combat skills and quiet determination.