You need to pull Berik to the front of the zone due to a port affect that happens after 50%. For us Berik is tanked in the middle at the top of the ramp and adds are pulled off to the side. The adds will knockback sometimes so tank picking them up needs to be prepared for it.
First half of the fight is pretty straight forward. Four adds spawn about every minute and need to be killed asap; if a second group is up at the same time Berik gets stronger. You will need at least two tanks on Berik due to the mem wipe/immunity every 45 seconds. Also no one can die that isn't being targeted by Berik. If someone dies from the AoE or a tank dies from the death touch it will spawn an additional x4 add. Your raid might live through one of these but if it happens often you will wipe.
When Berik hits 50% there will be a message saying that a change is needed which will add three elements to the fight. First is if a healer gets within 10 meters of Berik they will instantly die; also causes an add to spawn. Second would be the port which ports a random person to the top of the ramp at the beginning of the zone.
The last addition after 50% is Toxic and Tainted Blood. This is similar to the polar opposite effect from Rohen Theer. One of the tanks on Berrik will get a message "Danger, Tainted Blood can only be removed by mixing with Toxic Blood!" and a random priest will get the message "Danger, Toxic Blood can only be removed by mixing with Tainted Blood!" These two people must get into close proximity of each other; I think 3 meters, to not blow up the raid. Each player will receive the message "Your bloodcure has been removed by proximity to another!" when you are close enough. The two people MUST meet AWAY from Berik Bloodfist at least 15 meters. If you are too close you end your raid.
Remember you will need to designate a spot for your tank and healer to meet since the healer cannot get close to Berik. The other hitch that you raid might run into with the Bloodcurse is it hitting at the same time as the mem wipe. The best way to avoid this is to burn Berik past 50% when the mem wipe timer is between 15-5 seconds.
A player needs to have 430% crit chance to crit 100% of the time; 275% critical avoidance and a 55% crit chance debuff. Your raid is looking to have 3.8 million to 4.0 million dps to take this encounter down.