Champion Giant unaffected by Basilisk Venom
Whether something is either wrong or right, someone will always complain about it.
There are a couple of mobs like that. The Svanir shaman that is part of The Frozen Maw is like that too. Some mobs have a weird sort of stability that is not mentioned in their description.
Some mobs are also immune to other specific control effects or even conditions. For example, there are certain champions you will never see stacks of Torment on.
It’s unclear if this is supposed to be a deliberate immunity as part of the mob’s design, or just a weird glitch.
I should be writing.
It’s probably due to the innate buff that Giants have that make them immune to all control skills. Adult Karka have this buff too (although strangely the Karka Queen can be petrified).