The best starting point is to look up combos on the wiki and go through them to learn what combo fields the engineer can use, and how they apply them. The do the same for combo finisher. Basically to become familiar with which skills lay them and which skills use them. that would be the best starting point
Field creators are ::
Fire:
1) Bomb kit #2
2) FT # 4
Smoke:
3) Trait (Auto defense Bomb Dispenser)
4) Flame Turret
5) Bomb Kit #4
6) Elixir U tool belt (33% chance of thief smoke screen)
Water
7) Healing turret
8) Healing turret tool belt
9) mortar #3
Ice:
10) Mortar #4
Light:
11) Elixir Gun (kit refinement, 10s ICD on swap to elixir gun)
12) Super elixir
13) Toss Elixir R
14) Elixir U tool belt (WoR 33% guardian skill)
Confusion:
15) Elixir U tool belt (veil 33% mesmer skill)
Poison:
16)Grenade #5
Finishers:
Projectile (^20%): Hip Shot^, Explosive Shot^, Tranq Shot^, Throw Shield
Blast: Magnetic Inversion, Big Old Bomb, Throw Mine’s Detonate, Shock Wave, Detonate (any) Turret
Leap: Jump Shot
