I finally got to titanium, started with arrow block then tried to max out bow(to kill Spider Tron 6000) and made sure I had at least 1 clone at round 7 and 2 clones after round 13. for the most part I just kept moving killing whatever I could focusing mainly on archers and spidertrons. the jetpacks seem to be weak to walls and edges so I kind of exploited that to kill them. I died at round 16 :( \
update: got to level 17 mainly kiting large enemy force around while there archers/ spider bots friendly farm them then slowly eliminating spider bots and archers until only the main groups remain then I just slaughter them.
GOT TO ROUND 20