Runecaster will have some buffs in the future. If I’m not wrong
- Rune of Ice and Justice overheat increase to 2
- Rue of Giant have a chance to proc Earthquake skill when jumping
- Rune of Rock higher damage
- Rune of Destruction lower CD
Of course I’m not sure how strong it would be when the changes come but its worth noting.
If you want to have Runecaster, one of the more popular builds (also a build for one of my sub) is a support DPS build which is Taoist - Runecaster - Chronomancer. Chronomancer for obvious reasons for party support especially with Pass, Taoist for single target DPS and Runecaster for more AOE DPS which will get stronger in upcoming patches. Elementalist is a very good substitute for Runecaster.
If you want Onmyoji, Psychokino is a very good pick to go with to boost Gravity Pole with Firefox Shikigami. Last option could be Taoist for single target DPS, or Pyromancer for the synergy with the 2 classes (although you will be lacking single target DPS)
If you want dark classes, Featherfoot and Shadowmancers are viable picks as they are also getting buffed in future patches. You probably would need to include some summon base classes into them because of how well they synergize with one another.
I actually did a guide for the competition few months back. Will see if I want to update it when the future patches hit.