When City Constructor was spoiled I immediately thought "Chainbrei returns!" Playing chains or pit with city constructor on the field gets you two immediate and devastating empower triggers! Sadly, sling's presence in the meta has made everyone bring main-deck relic removal, so I had to splash primal for transpose. Wren is literally only in here because I've opened 4 and wanted to try playing them, sorcerer's wand is likely a better choice.