Pending Calyrex Clause

[iforgetwhyimhere :D]

Currently, there's a check performed on Obtainable rule formats that prevents multiple Calyrex formes from being used (due to the in-game necessity of the Reins of Unity Key Item). I propose a clause that can be added to custom challenges or tournaments that removes that check, and allows for multiple Calyrex to be used (granted that Species Clause is disabled, and multiple of the same forme can only be used if Forme Clause is disabled).