A 10 minute speedup for construction is an item in Evony TKR (The King's Return).
The description of 10 Minute Speedup for Construction in Evony TKR says:
Reduces remaining time on a construction timer by 10 minutes
10 Minute Speedup for Construction is known to potentially be obtainable from opening Lucky Box Ⅰ. The links for each item are below:
Note: This list may be incomplete.