nope i got frustrated trying it so i gave up...

Go back after beating Konquest mode. Every time you talk to him, you will take on the form of a different character. Some are more adept at performing long combos than others (I did it with Scorpion, though there's a thread on longest combos which show a few characters to have 14+ hit combos). I think you just get coins, if I'm not mistaken, so don't worry if you don't complete it.

meisly koins

It gave me 400 ruby koins. I did it with Liu Kang the last Jun Fan combo+ bicycle kick. 14 hits.
Ka-Tra

lei me is eays to do it also:
(first stance)
1,1,2, ,-> + 2
nice combo that bounces them up 2 times, hit them 3 times, then finish off with the fist of fury move. 12 hits guarenteed.
this is a very easy combo with no stance change (for people who dread those) also use this to do the kung lao 10 combo quest (earth realm) and the soyna 10 hit combo quest (chaos realm)