Magma are late game shields that come in 6 versions each one giving a HP and Attack(Basic) boost plus an increase to the versions STAT.
These Shields can't be used in PvP

+1

+1 Magma Shields will drop fully built in Return to Macro map.

+2

+2 Magma Shields can be crafted from fragments dropped in Inferno 1(Entrance) & 2(Ramparts). To craft a Magma Shield you need 3 fragments of the same version and a crafting coupon.