I was here for a very, very long time, and I fought every class on biochemist and on SinX before. So I know what works, and what doesn't,. For example, I know melee physical classes like sinx, and probably LK, will have a problem of getting dispelled. Now they cannot possibly wear GTB everytime they fight me, so that is where my valk randgris card is useful. I need something that pushes off people out of pneuma, cart revolution does that but I can't hit them with 405 hit, so I use phreeoni card. Now I need two cards on weapon that would help me against champs or any class that needs 195 aspd, that is where I use Thanatos maero. Acid terror carry over status ailments like freeze, so I use stormy knight. I get hit a lot in WoE, why not use dragoon wizard card then? 2x Dragoon wizard dont work, so I use amon ra as well. Only thing that annoys me about snipers is their arrow repel, so i have an rsx tao armor. So on and so forth.
Tons of the cards I use now, came from extensive testing of builds. That's why people will see me dead a lot of times in for_fild01, that was the time I am testing some stuff so I don't really bother wasting too many seeds. What I did before is research about the class, I didn't read any guide about biochemists before I used it. I tested it out myself. Checked every card in RMS and see what might help me(that's why i had darklord+dark illusion combo for my hybrid biochem before)
Oh and last but not the least, I never warped out in a duel. Even if my seed ran out. That helped a lot, knowing the ins and outs of pvp by not being a coward and warping out when things got rough.