You should NEVER gamble for TU's under any circumstances, if you haven't already gotten a TU scythe or runeword you can try 10 times, otherwise walk away, do it early levels in act 4.
I tested gambling offline and i rolled for 5 hours, Tier 2 rolls in act 4 which was macroed to make it faster : 3851 and no unique, that's not just bad luck that statistically tells you should never gamble for anything period. Some might get lucky maybe 1 out of 50 people but that's not gonna be you.
The hours i spent rolling for these i could have gotten to 100+ easily and by then my tu would have been obsolete, don't waste gold rolling for tu's, try it 5 or 10 times if you have no 2h already and then just keep leveling with runewords until one drops.
The t2 raptor scythes was 15-21k at level 60 it might be lower for you, but that's roughly 4k mystic orbs i pissed away on gambling to get a TU that can easily be farmed by killing bosses and more than 57 million gold, trust me it's not worth gambling in Median.