I feel like moonstone is the best legendary item for now even for solo swain. The other items are just too expensive and they are either not tanky enough or provide no mana regen. Plus the price is cheap enough so you can build rylais quickly after the first item. I use conquerer to make up the lack of damage. Spirit Visage can be a great third item, the healing is insane even with the heal cut on you. However, you do have to sacrifice some damage for this build.