I can show you one example how to do high burst in small period time and it is not easy counter against.
This video show you, you can make thunder triggered even with instant casts. I start with flare that make opponent heavy 3 seconds so you can freely continue cast another cast because target barely move during 50% heavy, after that use your thunder proc and swiftcast fire so you can make very high burst damage in small period time. Flare is doing 3425 damage, 2951 from fire 4, 2226 thunder, 2703 fire 4 and 354 thunder tick. That is 11659 damage. Flare land during 14 - 15 seconds and my last hit at 19 - 20 second of the video. That mean all that 11.6k damage came inside 5 seconds.
https://www.youtube.com/watch?v=szyw9SCcVYs