Found a really great way: taunt them and then counter.
Most of the time you will get a 1-hit-kill.
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I've found that keep pressing your attack and kick buttons alternating them every so often allows you to do combo moves.
I was able to do this for all five fights.
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How I beat this challenge: equip your throwing stars (or dagger), and hold down the attack button for a few seconds.
Ezio will crouch.
Release the attack button and Ezio will whirl 5 knives at enemies.
If there are at least 5 enemies within reach, they should get hit and die and you'll get the completion message.
Done within 1 second!
gaming.stackexchange.com/users/6547/Luke
Honestly, this part is extremely frustrating as your best bet for beating them in the alloted time is hoping that the game decides you are going to do a quick finisher combo instead of whacking all the health off an enemy one chunk at a time.
I found just mashing punch and countering only when necessary to work the best and was able to complete all the challenges pretty quickly.
Most of it is just about luck I found.
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Wait for the Mercenary to come to you, then continue to hit the attack button.
I used this method, winning lots of money.
Hope this work
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All guards are killed instantly with combo kills ("kill streaks") and counter kills.
To get this achievement, first find 5 enemies.
With the exception of Papal Guards, you may have to lure a group together.
You can initiate a fight by tackling someone.
After you have the guards, remember every kind of guard will be counter-killed with the Hidden Blade(s), including the Seekers.
After counter-killing one, you can use the killstreak to instantly kill the next guard, and the guard after that, until you reach 5 enemies killed.
gaming.stackexchange.com/users/10616/Joe the Person
I tried equipping my throwing knifes & holding down the punch button (square 4 ps3) but all holding down punch did was throw dust in their face which makes them stop & hold their head for a sec but after a couple times i noticed if i hit 1 right after throwing dust in their face Ezio will do a 1 hit
k/o do this 2 all of them & once u get to 4 try to take out the one on the far left first
he's the one that'll dodge ur attack everytime.
Hope this helps!
gaming.stackexchange.com/users/106366/megan
In Brotherhood the fight missions for Mercenaries have a very short time limit on them. What do you need to do in order to win the fight in less the 10 seconds? I been trying and trying and can't seem to be able to do any significant damage within 10 seconds.
How do I beat the "Kill 5 guards within 10 seconds" mercenary challenge?
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<assassins-creed-brotherhood>
gaming.stackexchange.com/questions/11562
gaming.stackexchange.com/users/2874/Lukasz
Keep pressing the attack and kick buttons. All guards are killed instantly with combo kills. Your best bet would be combo moves and counters, together with taunting or kicking. Another way could be if you wait for the Mercenary to come to you, then continue to hit the attack button.
Combo moves seem to be the best way to do this. Another user suggests hitting the attack button after waiting for the mercenary to attack you.