Raiyuu, Storms Edge If you specifically want to build around samurai as a creature type, Isshin, Two Heavens as One definitely works, though Raiyuu, Storm's Edge is friendlier on the budget
The borderless version is already pretty pricely, so I think theres more value to be gained in the regular copies, but if you have the ability, Cloud holding his sword is always going to be a big draw
So think of Sol Ring as the snobby spoiled rich kid who gets away with everything and has total immunity because of its status
Costing six and not being able to immediately gain any life means you will have to do quite a lot of work just to get to stage you can make the Wurmcoil with any semblance of safety, if at all
Instead, you can use Donald to quest for three lore each turn and start leaping at that finish line