I don't know about you guys, but I seriously feel glu should enforce some kind of fail safe when farming for the extremely rare items, like if it doesn't drop within 1000 kills, you should be Guarenteed to get the item on the 1000th kill.
Get good lol :p Jk but seriously, tower would hold no challenge whatsoever if there was no eyes or marksmen. If you haven't figured it out by now you need to immediately and selectively wipe out the flaming archers, eyes, and regular archers higher in tower.