Really need those gem, and i just wanna know where to farm it in term of AP efficiency. Should i just farm it on the daily quest or on the Underground Factory in the summer part 2 event ?
I need those too. Honestly I think it's better in the training grounds with 60% drop rate while the underground factory has only 15% drop rate, so I suggest not doing what I did and just go to the training grounds or wait for events selling skill gems or maybe the Christmas's lottery which gives skill gems.
The Lancer Training Grounds Expert and Advanced are your best bet(Expert having a higher chance of course)
Here's a spreadsheet for every drop in FGO which also gives you AP efficiency rates on nodes that drop specific materials, cheers!
https://docs.google.com/spreadsheets/d/1_SlTjrVRTgHgfS7sRqx4CeJMqlz687HdSlYqiW-JvQA/view
