But in fact, Sola's opinion of him was not solely flattery. The secret technique Kayneth prepared for this Heaven's Feel had completely overwritten the rules of the war that had been designated by the 'three original families'.

Originally, there is a cause and effect line between Servant and Master. A technique to separate the right of Command Mantras and the right of supplying prana, letting two separate summoners control one each... by way of Kayneth's prodigious ability, this impossible technique was made possible.

Kayneth is the magus who owns the Command Mantras, yet the one to supply the Servant with prana is none other than... Sola. They can be said to be a two-person team Master.

- Fate/Zero: Act 5, Part 2