You can find some cool Addons on this page : https://alloder.pro/files/category/1-addony/
1. ShowDD: This is paid addon who cost 0.36 euro for 2 months of using, it's replace yellow hit numbers for more cool loking nubers, also adding pictures for what spells your hited that much dmg, of from what sorce you got dmg on your face, you can improve your enginner gameplay experymenting your dmg and def with it https://alloder.pro/files/file/49-showdd/
2. DarkDPSmeter2: Showing how much dmg/healing you do per sec, also same showing your team or raid, so you can see how good or bad you are compare to your team
Thers many other addons you will want to look at, but i'm mentioning thes, as thay will benefit your engineer gameplay the most
Offtopic addon can be Cartographer, he will help you get +1 ruby from Engineer Trainer, and display chests on ai-rihat map, also can be modificed to show herbs if your alchemist