For the record Killing Spree is the most annoying skill in WoW for a boxer. As of the last time I spec'd combat, it not only breaks follow but also removes that player from /focus in all ways. So you have to re /focus before /follow or anything like that. PITA

And ya that talent can wreck things. I imagine 5x killing spree may even have a chance in arena providing you can work out the end of the match with 5x melee.

Killing spree as of 3.1 (i believe) is going to raise all damage done by the rogue 20% during killing spree. Sooooo.

Walk up in stealth; 5x Tricks of the trade in a circle (all 5 toons get the benefit 15% dmg); 4x garrote 1x cheapshot; 5x killing spree; should raise your bleed + poison damages by 20% along with the 15% from TotT, with all that flying around you could potentially drop half a team of clothies in 1 attack.

however if you play it right with shadow step + shadow dance you could walk up and 5x Ambush a clothy for an instant kill. Then press a shadowstep macro that will automatically Shadow step + Shadow Dance + Ambush a second target for 2 kills in 2 GCD's then with shadow dance active you can bull charge another guy and use premeditation to fill a few combo points and drop a Hemo with your leader running through him and 4x Eviscerate on them with the slaves that should be 50%-death depending on the target and his gear.

In a perfect world you can see how this could be sudden panicy death for multiple people and i have plans to do a 5x rogue team soon to try the following.

5v5 arena:
Close in on opposing team, activate cloak of shadows + evasion + sprint + Tricks of the Trade
1st target: Walk up. 5x ambush
2nd target: Shadow dance + shadow step + 5x Ambush
5x /target nearest /cast blind
3rd target: 5x premeditation 5x Eviscerate or possibly have leader use hemo and clones eviscerate. This may not kill the target but I would move to the next target anyway to keep the chaos
4th target: Aquire target, 5x Preparation macro ( uses every skill preparation resets: sprint + vanish + premeditation + cloak of shadows + shadow step + dismantle) and then press it again to activate all of those skills which vanishes and shadowsteps your target and then 5x ambush
5th target: may very well be crying and/or sucking his thumb at this point and you can just shiv him to death or what have you.

On paper this looks like a good 5v5 strategy but when I tried it with 5 solo played rogues the timing and target selecting was an issue and we fell apart in the 1900's