Ok, dumping speed on Eldigan is the way to go so +atk and -spd is very good if not the best for him. For seliph, I personnaly would take 1000 feathers for him. He just has everything a bad unit wants. Unless you like him, you should probably pass as he needs a LOT of investment to be mediocre. If you lack red, you could build him for Arena assault for now but a very simple and cheap build.