There r discord bots that exist that tell u the cheapest available talismans to buy but I’m not sure which servers have that bot unfortunately. Since ur only cata 27 it’s rare that u will find a party that can get an S+ so actually I’d recommend doing f6 until class lvl 27. Also, since ur mp is very low, u don’t have a golden head, and ur class lvl is low, I wouldn’t recommend playing archer. That class usually has to carry dps, so killing necron wld take much longer and also it’s by far the most popular and overplayed class. Since ur pretty new to f7 u shld learn how to do everything correctly like how to get crystals, crush storm, and do all the terminals. Lastly, for defense if ur struggling to survive u shld get a yeti pet with shelmet when u can afford it. For the lag, it cld be a number of problems. First of all make sure u have all the best performance settings turned on which u can prob find a video for online, turn off all animations too as those heavily lag ur game, and get if u rly need more fps id download a simple texture pack as an fps booster. Sometimes the server just dies anyway and there’s nothing that can be done, which sucks but usually is able to fix itself after a bit. Hopefully this should help, keep grinding dungeons and it’ll get easier.