Since I don't seem to find INT Majin builds in english I decided to make mine.
Stats: Full INT
Demonic Gift (MAX)
Armored Bracer (MAX)
Evil Spirit (OPTIONAL)
Note: You don’t really need more Max MP, so I suggest saving your SP for other skills and not getting Evil Spirit at all.
Hellbringer Corruption (Level 1)
Dark Spark (MAX)
Power of Mephistopheles (MAX)
Battle Heal (OPTIONAL)
Note: Dark Spark is your only buff, but in order to use it you need Hellbringer Corruption level 1. Power of Mephistopheles is your most important skill. Without it you can’t use any of the other active skills.
Tooth of Tundra Ice (MAX)
Noxious Cloud (MAX)
Note: Tooth of Tundra Ice has a high chance of freezing your opponent, which makes it really useful in PVP mode and in boss fights. Nocious Cloud, Destruction and Immolate do not require you to select a target in order to use, which is a great advantage because that way you can spam those skills while selecting your character, allowing you to use Battle Heal more efficiently.
Use Pinsir unless you don’t learn battle heal, which might not be a good idea given that battle heal will be really helpful. In that case you will be able to construct Staffs with Shipwrecked materials that can be used by Majins and give you more Magical Attack Power.