Invasion could use more gold.
Right now you get, what, 10k by the end? You can't even reach full build as a support. And I believe all gold generation is actually taken out of your pay.
If you ever actually reach the boss, and unless you bought the very cheapest items, you still have 2 or maybe even 3 slots open.
More gold would really help the difficulty of this mode without having to make more extreme changes like changing spawns or stats.