Luden´s Echo - It´s your go-to item. It has the burst, the mana and the Echo passive, beeing the best mythic item for her and beeing very similar with the AP Item jungle, wich was a huge power spike for her

Cosmic Drive - Cosmic Drive is very similar to your Spellbinder. I would recommend building it after your mythic item if you are behind

Horizon Focus - Horizon Focus is a very nice item for more tanky or immobile compsitions where you can pop your charm with more ease

Banshee - Banshee sinergize really well with Mejai´s. It give you a really good AP amount and it helps you to maintain your precious stacks

Lich Bane - Lich bane is still very strong, I would recommend building it for more flat AP, instead of Mejai´s

Void Staff - Void Staff´s build path is a MASSIVE buff. Future´s Market on the little void item it´s a really strong back to Evelynn