Gems to builder potion is not at all a good value. 285 gems to save 9 * 6 hours of progress (assuming you have the sixth builder) is a cost of 5.27 gems per hour OR if you are using the goblin builder that is 4.5 gems per hour The best usage of gems is no doubt the book of hero from trader which can save 8 days for 500 gems costing only 2.6 gems per hour and even better is the goblin builder who costs like 1.67 gems per hour. and please do not keep one builder free at all times that is seriously going to increase the time for you to max by several months if not years. i might as well lose the extra loot because of full storages but have all my builders working instead of the other way around. it doesnt make sense to prioritize something like overflowing storage wastage over progression. just space your builders properly if you are facing full storages.
