Psorek once suggested a srine-enhanced killgem could be like 800 times better than a normal one. I just realized that U4 is the perfect spot to do it, and a very nice field for XP-run at the same time. I have been playing enough and won't do it but maybe somebody else wants to do it ...:
The 'shrine-zones' intersect at the top of the map. So probably one could play a normal game, but then + freeze the last 5-15 waves. A couple of them for the manafarm the rest for the shrinefarm + then one could remove the slowing gems there, so lag shouldn't increase too much + at speed 9 it should be possible to enhance a g1Y and g1B like 20 times or so, maybe enhance R a couple of times, too
If somebody tries I would love to se a pic of the resulting killgem ...