BioShock 2

In multiplayer mode, BIg Daddy suits spawn randomly around the area in which you play.

This achievement is given for killing the person in the Big Daddy suit.

Now, that sounds simple enough, but in MP, Big Daddy's are horribly powerful compared to the rest of the players, so it is very likely that a front on assault on the player in the suit will result in you eating from the pointy end of his rivet gun.

So what you need to do is step in at the right time and finish the Big Daddy off when he is damaged. Level of damage will appear on screen so all players can see it.

Once the person in the Big Daddy suit has been worn down a bit, step in and finish them off. Try to get close without them noticing you so you can get in some good shots with plasmids and weapons before they can react.

The best way to go about getting this is in a team environment. In free-for-all, you will be shot and killed by anyone if you camp out and wait for the Big Daddy to be worn down. But in a team environment, I have found that teammates will often work together to try and bring down a Big Daddy to improve the chances their team will win the game.

When this occurs, get in a spot comfortable to you and open fire to do your bit to wear the Big Daddy down. Obviously take cover to avoid dying. When the Big Daddy's health is low, try to step in and finish them off.

I've actually found this to be easier on a free for all match. Mostly because you can stalk the character that has the Big Daddy until he is low on health then let him have it. If you can't manage it there, try on the Little Sister capture level, as the defending team always starts with a Big Daddy. Just remember, they are much stronger than you, so pot shots are a must. Incinerate works pretty good for this, or just long range shots until you wear him down.
Again must be done on a public match.

I have found that the best way to kill a big daddy, though it will make people mad, is play on civil war and let your team take him down to a slither of health while you stalk him, then run in with a grenade launcher and winter blast.

When taking down a Big Daddy player, you can do one of two things:
1. Go in after every player has practically finished him and land the final blow before someone else,
OR
2.(Recomended) Pack heavy, and help other players take him down, Plasmids such as Insect Swarm and Incinerate! work well,because of thier lasting properties, And when the Big Daddy is low on health, and timing and speed is everything, RUN behind him without him noticing and stay behind him, doning damage with Melee, your weapon, and plasmids, until he falls! But caution, If he gets smart and does a stomp, there is a split-second for you to jump over it, but timing is crucial! Hope this helps!

Big Daddies spawn in most game types, but I'll focus on Civil war, since it's the only thing anyone plays anymore. Here's a few tips for dealing with them;

1) Turrets; Big Daddies greatest weakness. Without plasmids or regenerating health, and with the larger frame making it harder to hide, they can either ignore it or focus on it entirely. It doesn't matter which they choose, the turret can still easily take out half his health fast. Vending machine traps are less effective, but still helpful.

2) Cover, plasmid, cover. Use your regenerating health to your best advantage. Charge up incinerate, duck out of cover, fire, and return. Incinerate is the only one of the starting plasmids that will work here. This way is very slow, and you're vulnerable to kill-stealers.

3) single-player style; just like in the campaign, use shock and freeze on him, then open up with your best weapon. Note that big daddies already turn slow, so slowing him further with with a plasmid will make strafing even more important. I once saw a player melee a bid daddy to death by shocking him and running around in a circle, but that takes a lot of skill.

If none of these are available to you, it's still worth it to shoot at him. You could get lucky, and even if you hit him once, you'll get credit for an assist. It's also worth mentioning that, although he loses all research bonuses when he upgrades from splicer to Big Daddy, you don't lose yours on him. If you're lucky enough to have a bonus on him, taking him down will be much easier.

You could also boost this. It should be pretty obvious how.

This achievement is earned by taking down your first Big Daddy in an online ranked match. For this achievement you'll need some skill and strategy.

So naturally someone will take the role of the Big Daddy when they enter the suit once it spawns into the game. Given the circumstances the enemy team will have to be in control of it. Now as far as taking it down here are some things you should know:

The Big Daddy has 6 proximity mines, which also explode on impact of an enemy player, a rivet gun which has infinite ammo, but an overheat feature, a foot-stomping stun ability, when you're within range, cannot use plasmids, and does not replenish health. Also whoever becomes the Big Daddy loses all their damage bonuses they earned prior.

So given the factors the Big Daddy is a formidable adversary, but not an unbeatable one. For this achievement the factor will be stealth, overpowering, and the strength of numbers.

A good way of dealing with the Daddy is having your teammates weaken or overrun him. This will cause panic at times and resort to the Daddy using too much shots and overheating his gun, or being dysfunctional with all the enemy attacks. Another way is by guerrilla warfare, using the Houdini plasmid will give you invisibility, so doing by an attack-retreat method would help.

Also there is a tonic that increases the damage dealt onto a Big Daddy called Big Game Hunter and it can be unlocked at rank 36. Using that with an automatic weapon like the Nail Gun or Tommy Gun would definitely show significant results.

NOTE: Credit for killing the Big Daddy will ONLY go to the player who deals the FINISHING BLOW for the kill onto it.

Upon collapsing the giant Tin-Man himself you'll unlock this 20G achievement.

The following video is of my semi-match and my first killing of a Big Daddy in an online match.