Punishment of TK should be this:
If you tk a guy in 1 round you won't get any exp/gold from next tick.
If you tk 2 guys in same round,you will miss next 2 ticks.(Punishment adds onto previous punishments.)
If you TK 3 guys in same round which means you are really acting retardic,you won't get next 5 ticks.(Punishment adds onto previous punishments.)
Let's say you TK'ed 3 guys in same round,you won't get next 8 ticks in total.
1=You tked for the 1st time
2=You tked for the 2nd time
+ 5=you tked for the 3rd time
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8=You won't get benefit of next 8 ticks.
If you TK for 4th time in the map you'll see a warning (Purple admin type style) which tells you "on your next TK of this map, you'll be auto kicked." You won't be punished by loss of ticks on your 4th tk,just a warning.
If you TK 5 times in 1 map, you'll get auto kicked out of the server.(+Maybe some money or exp loss penalty)
I think this should work. It's not abusable,it'll improve teamwork and let people play more cautious especially when your team has x3-4-5 cuz no one want's to miss those ticks =) Which will reduce chances to lose multi due to a spammer tk'er retard.
My english is not so good i tried to explain what i think i hope i did well and i hope you take my suggestion serious because i think this'll really seal the TK deal.