I've been playing primarily FS/IG for about 6 months now, prior to that I was a meme FS/GA build (for fun), and I've dabbled in IG/GA and FS/Rapier.

I run light with hearty, 5 resil, 4 freedom, 3 physical aversion/2elemental aversion, along with the 2 purify traits (one hits when using a regen pot, the other hits when I dodge). I've shifted away from being a glass cannon (only 2 refreshing pieces), to doing sustained DPS, and being moderately tanky with the above build. I do not run flamethrower at all, and still play as a dive bomb mage. Assuming at least 1 or 2 reasonably competent healers are on your team, its hard NOT to get the top 10 in this build (OPR), at least for me.

My hard matchups:

SS/Blunder- Dodge/block leaping strike, Entomb if it gets sketchy. Ice shower and get distance/go for the kill.

Bow/X (especially rapier)- This one is hard, I usually try to go toe-to-toe with bows, and probably 70% of them will have the upper hand. If I am popping pots I can consistently kill solo bows, but they typically travel in packs. Honestly against bow I prefer to just LOS and use area denial (shower etc) vs killing them.

LS/Rapier- Unless you play perfectly, this is a very hard kill. Usually need teammate support, but you can effectively lock down 1 healer as a mage, which can possibly turn the tide of battle in your favor.

LS/Void- No dice. Similar to LS/rapier, but better healing capabilities. Going toe-to-toe is a likely death sentence. Must play ranged against this build.

GA/WH- I can 1v1 probably 80% of these players (even with stam changes). The good players can sometimes catch me/lock me down, but its uncommon. A few melee with Stuns/Grav wells? That's probable death.