Support. Use Spark Wraith off cooldown to harass the enemy. Flux does a lot of damage but will only work if the target has no allies (including creeps) within melee range of them. Arc Warden's ultimate allows him to clone himself, but don't bother leveling it up until you at least have Kaya, which should be around level 9. Once you have meteor hammer, use meteor hammer on large creep waves or enemy towers and then select your clone to do the same. Make sure the first meteor's DOT wears off first as it doesn't stack. You can keep your clone on auto for the most part except for the meteors. Magnetic Field protects allies inside it from ranged attacks, use it to protect your own towers or aggressively against ranged heroes.