1. It’s almost always better to use Luck stone to improve your Wartune gear upgrade chance. Especially when gears become more expensive. For higher level gears, +9 to +12 can cost you something around 200k~500k or even millions. Using a Level 3 or Level 4 upgrade stones can half that cost.
2. At lower upgrade levels +1~+4 the luck stones are a waste of money.
3. If you purchase Luck stones from guild shops and synthesis them to highest level, by going for 100% upgrade will end up costing you more Gold in the long run.
4. Higher level guild shops are extremely important in gear enhancing due to cheaper Luck stone.
5. It is important to find the break even point between enhancing directly and taking chance. I have designed a spreadsheet to help you figure out when and how to use certain level of Luck Stones toward gear enhancement.

It should be noted that I did not make this calculator to have any fancy functions because I want it to be straightforward. It helped me to determine how to enhance using the least amount of Gold possible.

You can google for Wartune Gear Enhancement Calculator by Gamelytic or use the following link.

Wartune Gear Enhancement Calculator

Let me know if the value in the calculator is wrong is anyway. Please feel free to give me any feedbacks.