Need help on agro control!!

There is a current build that my friends and i have made, the only problem to it is that the agro doesnt stay on the assasin. The assasin has shadow form on him, and we can not keep the agro off the others.

Please post any ideas or commonts in which u have for my problem. Thanks in advance for any solutions u have provided.

The rest of your group must never enter tank's agro bubble.

For this, the tank will need to body block all mobs against the wall, and casters will need to move in and out for casting.

There's no other way to hold entire agro on with a single tank.

Look around for Stygian Veil or Ravenheart Gloom builds/strategies.

thank you if people have more or different ideas please post