Jathro said:When an ATK and/or DEF value of "?" is used as an equip, it is counted as 0 for those purposes.
Great Maju Garzett would have an ATK and DEF of 0 if it was summoned by tributing a Megarock Dragon. It doubles the original attack that was printed. 2 x ? = 0
Same goes if TER sucks up Megarock Dragon.