WALL OF TEXT !!!
hello , if you wanna LEVEL your perk fast , do Defence-b2 BLOAT"ed mutator HARD or Suicidal just camp at upstairs and let them all burn , stocking Flamethrowers may help you , also try to use fire grenades as they can kill Bloats after level 4+, its easy-fast level up if you play constantly , like 10-15 hours , keep doing waves 2-6 and repeat , dont play 7 because of the Fleshpounds that would rip you .
i'll explain why to do some things and the oppost of each.
Solo : heres the key , if you play with all specimens itsnt that good , make your own room with Bloat'ed only and no one will steal your kills or "KS".
defence : this map is big and good to firebugs , just do BLOATED only , Hard or Suicidal depending on your level , burn them in mobs staying at upstairs , sometimes use grenades when level 3+ (fire-grenades) , last tip doom-final 2 isnt good as how defence is , because defence map provides the best mobility-escape map and you can burn the bloats before they reach your floor ! repeat waves 2-6 straight and level 6 will come soon.
PLAY HARD OR SUICIDAL : according to your level its better and more effective when you play at suicidal or hard depending of the level. Bloats on Hard or Suicidal are the best way , and always ALONE(Solo) ! as they have much more HP and that gonna level you really faster than the Easier Ones.
Any Doubt add me on steam "Gamecs2" but identify yourself before.
Hope i helped you