I have 1 on a mountain in the winter biome where i live, i was flying around it to check it out and it almost killed my pterra in 2 hits. It had 80,000 hp, i dnt knw what lvl it was, but my tip is, dont under estimate the power of the giga
NEVER AND I MEAN NEVER make a large base near mountains especially volcano and mountain on top right of the map gigas would spawn there more commonly so don't have large vases there if u do don't say I didn't warn you.
If one is encountered near water, you can simply lure it out to sea with a flyer and it will swiftly drown. Given the water is deep enough. If encountered inland not near water. Pray to the overseers you have something fast enough to out run it. Then promptly die because they're as fast as a mad Hispanic mother with a shoe. Not as deadly as one though.