[Hoplosternum]

I think in general if you want an SC there are better choices than the GK. And if you want a Rainbow or artillery support mage Pretender there are better choices than the GK.

That really leaves just those nations that need an SC but also needs magic diversity on their pretender. Jomon fits the bill here for one. They completely lack Death (gems or paths on mages) and need it for most of their summons. They also need other paths to recruit some of their better summons (Fire & Death for Dai Onis for example). They also need an SC to make up for their poor starting army and high resource costing troops.

A GK works quite well for them. They don't really benefit much from a bless (none massable sacreds and mages not sacred) and their starting army can support the GK to make up for the fact he isn't top draw in the SC department.

Jomon also can't get a Prince of Death which would otherwise be a better choice. And Lichs or Master Lichs won't really handle the SC/army support side earlier enough to be viable.

So I think he is a niche pick at best in mp. Jomon being one power that can benefit. As the combination of SC, then site searcher, then summoner/forger works well for them. In sp of course his flexibility makes him a more reasonable choice.