Having a 6-star monster is the ultimate goal in Summoners War. It is not easy to get a monster to 6 stars but here I will give you some tips on how to reach it as fast as possible.
1. Farm Faimon Volcano Stage 1. Make sure to pick a strong monster as your leader. I recommend the Fire Inugami.
2. Choose the monsters you want to level up. Keep in mind that the goal is to 3-star, 4-star…etc as many monsters as possible. The best time to do this is during a double EXP event.
3. So where do you get the monsters to level up? Summoning scrolls. Also a big advantage of Faimon Volcano is that the Fire Hellgound is a very common drop. This is a monster that will be ready to level up to 5-stars and eventually when you have five of them you can feed a monster such as the Fire Inugami to make it 6-stars.
4. Now you repeat this process over and over again and level up whichever monster you want. The higher the level of your main monster, the faster you will be able to evolve the low level monsters!
TIP: Fire Inugami had a passive ability which makes it able to attack again with a random chance & once again once he kills a monster. This makes him the ideal power-leveling monster!