You're 22 levels above Taken Disciples. Can you solo the whole wave and kill the disciple with only level 18 weapons equipped, or does a 22-level advantage mean something less than what you thought it did? This is analogous to starting at the beginning using the spark. Yes you are 22 levels above Level 3 enemies, but the only weapons and armor you have been given are the same ones you would get at that story level without the spark. I'm not saying it doesn't offer an advantage, but a lot of people seem to believe being level 25 with level 3 weapons makes you a god against level 3 enemies; it doesn't in my opinion, with which you need not agree. Good Luck Guardian!

How do you know if someone used the spark?

You can look at his stats. First mission he ended on being level 2, second mission he was on level 25. So basically he used the spark so he was overpowered. Nothing wrong with using it but it kinda defeats what he's saying.