hello , would you recommend me any build .

Also does any sunder charm that helps ? The fire one?

Max corpse explosion and melee skeletons plus its mastery.

what would be better for the merc , botd or infinity?

infinity since half of your CE's damage is fire damage. Andy's and fort

Little to no gear go summoner otherwise poison nova with maxed ce and 1pt in revive clears density pretty well

Infinity for merc helps ce clear faster

every necro build is a ce build, just depends how you wanna kill the first mob

Ok , what kind of damage is corpse explotion ?

Do the new charms will help and increase my dmg and merc dmg?
Black Cleft with Magic resistans and Bone Break with Dmg increse?

Corpse explotion is 50% fire damage and 50% physical.

Sunder vs phy
Synder vs fire
Infinity
Amplify damge
will deal most dmg