There are numerous variations of Daeja you can play depending on the mirage.
While Daeja's itemization laregely stays the same it can differ based on the mirage.
If its warlords > you want to prio crit items on deja
Dawnbringers > Items that stacks over time Arcangels + rageblade + GS
Duelist > Heavy damage items GS , IE ,JG
Spellsowrd > attack speed items plus healing > Rageblade + QSS + Healing item (ragblade core)
One of te best items you could use on Deja is Whisper: