Construction (31 Skill Points)
Healing Bot (15 Skill Points)
Almost any Engineer has it. You and your party will benefit from early to higher levels.
The skill is also economical since you will use lesser health and mana potions.
Fire and Spark (15 Skill Points)
Tip of advice; learn this skill on higher levels where you have lots of fire and electric damage from skills and weapon.
Boost your overall damage. Just make sure that the weapon you are using has electric or fire damage.
Charge Domination (1 Skill Point)
Single point in this passive skill is enough. Don’t waste additional points since you get more chance if there are more enemies.