When mission starts, put down basic buffs without empower. Kill some enemies until they drop energy orbs. Empower then collect energy orb for extra 100% ability strength (total 448% strength). Just remember: EMPOWER THEN ENERGY ORB. Empower AND [Energy Conversion] only gives 50% strength and CANNOT be increased by strength. Hit the enemies until [Growing Power] proc (+25% strength), then place down buffs.
If you don't want low range, use [Narrow Minded] with lower rank.
You can use any arcane, this is just recommendation.

You can take this build to another level by playing in fissure/open relics. When collect 10 reactants, you have a chance to get extra ability strength and range, great for endless missions. Or just wait until arbitration give bonus 300% strength, bringing it to 773% strength.