How to bring Mr. X on his knee?

[Kaidan]

I saw there is a challenge for it, so how do I do this?

[Grey]

Shoot him in the head enough times. Not hard.
Don't use nade launcher , it's not effective and a waste of nades.
Use a 9mm gun/smg, or a shotgun from really close.

[Kaidan]

forgot to ask: Is this only during the final battle? Or can I also do this after the first encounter?

[D I A B L O]

save ur game, then shoot everything u have at him, unlock the achievement and then reload the game so u have all your stuff

[Grey]

Originally posted by Kaidan:

forgot to ask: Is this only during the final battle? Or can I also do this after the first encounter?

You can do it whenever.
And I don't even remember if you even can do it during the final battle.

Originally posted by X x X:

save ur game, then shoot everything u have at him, unlock the achievement and then reload the game so u have all your stuff

There's really no need to cheese it. I did it the first time I played and didn't have to unload everything. Doesn't take that much to bring him down. But he could do that too if he is running low on ammo.

[Chaoslord 87]

Just keep in mind, that this will take him out only for a short time before he gets up again. It`s generally better to avoid him as long as possible( slow walking and not shooting) or stun him with a Flashbang and get the hell out of there.

[BOWSER]

Well, I'm not recommending this or anything but on my first play through on Assisted, I clearly remember 2 grenade rounds would bring him to his knees. Maybe you can use that as a reference to how much ammo the other guns would require for the same result.

[YUREKA]

Mr.X is weak against acid round, if you play on standard use 1 acid round and a few hg bullets to the head. it takes 2 acid rounds on hardcore tho

[talgaby]

Deal 1500 damage. The coat has 80% damage resistance, but only against hitscan weapons. Acid rounds are surprisingly effective, while Leon mostly has his starting handgun (it has a somewhat larger damage bonus than Claire's).
Keep in mind that his kneel animation lasts only 30 seconds, after which he will start to pursue you again. Also, getting the jack handle seems to instantly cancel it, but so far I haven't found any other trigger that does the same.