[Metathron]

As far as I remember, the guardians of this amulet are pretty weak, so you shouldn't be far away from being able to defeat them with your level 4 hero. Perhaps another level or 2 will make you stronger.

What's your army composition? Which class are you playing as?

Have shooters, so you'll be able to deal with the towers as soon as possible, especially the red ones (evil gremlin). Archers are an obvious example. Thorn warriors are also easily available.

Troops with a magical range attack, such as priests, inquisitors and archmages are not a good choice, because the towers seem to have some kind of resistance to that and these troops will do puny damage. If you do choose to take any of them, use them to attack enemy troops, or reinforce your other stacks with beneficial spells (magic shield, bless, heal...).

Also, as Zuvio said, it's a good idea to enter the battle with a good amount of rage so as to be able to cast evil shoal, because IIRC the towers in this battle have low hp so they'll fall like flies. In many later suppressings, this couldn't work, as you'll face towers with 4000 hp and more.