A great Background to pair Laelia with is Passionate Archaeologist, which lets you burn an opponent every time you cast a spell from exile
And at that point, is the difference between nine or ten power from your pump effect that big a deal
Zegana also pairs really well with high-powered green cards like Ghalta, Primal Hunger, which can enter the field before Zegana and give you 12 cards in hand and 12 +1/+1 counters
Secret Door is a good early game blocker and in the late game can help you venture into the Dungeon possibly multiple times per turn
It'll still have menace even if it stops being equipped
They decided that this slot, along with the card that would become Inscrutable Sphinx (version #4) 4UU Creature Sphinx 4/5 When CARDNAME enters the battlefield, look at the top five cards of your library and separate them into a face-down pile and a face-up pile