The coordinates for the base are 2648 x 3421, it is right above the Crater Lake as shown below.

X marks the spot

Entrance to the Sentinels Base

You will find Frederickson at the top level of the base at the very end of the upper row of barracks.

The star marks where High Commander Frederickson is located.

Right lick on him and the conversation dialogue window will open.

In the course of your conversation he will tell you that the sentinels are worried that Omni-Pol will attack their base, but that he is short on reinforcements to help with a counter assault.

Tell him that you are willing to lead a party of loyal clanners and assault the base.

He will thank you and then mention an Omni-Tek General, Kaehler Jr. It seems that this Kaehler murdered Frederickson's sister and he wants nothing short of revenge. In fact he wants you to serve the general's head up to him on a silver platter!

If you accept you will be given a mission with a nine hour limit to deliver the head on the silver platter back to him.

I guess it's off to find an Omni-Tek General then!

Kaehler can be found in the secondary omni outpost in Avalon, but be warned he is over level 200 and in a very heavily defended base, getting to him is going to be no easy feat and require several well organized teams. The outpost can be found at coords 834 x 1681 in Avalon.

Arrow point where he is usually located.

He is not an easy target.

This base, like it's larger counterpart in Avalon is very well defended, and has Omni control towers at the entrances, the southern entrance is slightly less heavily guarded, but either way you try and go in it will take a good amount of effort to fight your way in, or draw him out.

I would not recommend fighting in and around the towers, whilst they do less damage then some of the guards they have insane amounts of hitpoints and are better just being avoided.

You will have to be well organized and able to last the pace if you are to get through and kill Kaehler, if you are successful however, you should get his head.

Head of General Kaehler

Now all you need is the Platter!

The Platter drops off Trader Eel also in Avalon at the main Omni-Tek base there. Be warned he is almost as tough a kill as Kaehler is and the tactics required should be similar.

A Silver Platter

Combine the head with the platter and you will end up with this:

General Kaehler's head on a Silver Platter

Return it to Frederickson, he will reward you with the Superior Sentinel Body Armor which you can see the High Commander himself is wearing.