When Worldwalker Helm enters the battlefield, Replication Specialist triggers, causing you to pay ({1} magic symbol) ({U} magic symbol) to create a token copy of Worldwalker Helm and a Map token.
Activate Urza's first ability by tapping a Worldwaker Helm and a Map, adding ({U} magic symbol) ({U} magic symbol) .
Activate a Worldwalker Helm by paying ({1} magic symbol) ({U} magic symbol) and tapping it, creating a token copy of the Worldwalker Helm token and two Map tokens.
Activate Urza's first ability twice by tapping the Maps, adding ({U} magic symbol) ({U} magic symbol) .