The "TWO KIDS IN A TRENCHCOAT!™" is a phenomenal, REVOLUTIONARY spell made by the one and only Balthazar Quenyasen! The sorcerer extraordinaire that has been rocking the world of modern wizardry in all of Senema!
The method is simple, yet requires at least to willing creatures to be fused into one!
A wizard casts a spell that transforms 2 humanoids in a single being. A small dance from both parties (no synchronization required) should be made while both voice the word "FUSION!". The caster can customize their appearance while the spell is cast but can't change the new form at-will after the process is completed. It is a concentration spell that requires the focus of both members. Once transformed, they obtain the best of both worlds. They have the highest stats of both members, they share all proficiency and understand both languages, as both minds are connected. But, because of that, the minds also share their weaknesses: Addictions, nightmares and physical needs will come along. If the casting is performed with no specific appearance in mind, then the result will be a mixture of both members' appearances.
If they take damage, both members of the "Trenchcoat" will feel the same repercussions, but, when rolling the Concentration check, the bonus for both members are added to the roll. The new fusion must have only one turn but has access to all their abilities and all of their spell slots combined. The spell can also be cast in combat but requires the caster to spend a turn preparing for the dance, and fusion will only be complete when the partner spends their own turn performing the dance and completing the spell.
The fusion is a powerful being, but do not overestimate its capabilities! You are still giving away one out of two turns and the damage that you'll take is essentially doubled.
Nevertheless, the "TWO KIDS IN A TRENCHCOAT!™" method can be a powerful tool for social encounters as well as in combat, when used wisely!