If you want to tame this Guy Follow These Steps

1) Find this Guy on Mountains (Commonly on Giga Mountain In Ice lands)

2) Come with your Argi, Giga don't attack argies unless you attack them

3) Bring 6-8 Metal gates and 100+ Narcotics/Bio Toxins

4)Trap the Giga With metal gates (Don't Dismount From your Argi Or You Die)

5)Wait For Night And Take A nap Near Giga

6) When you wake up Just Hit With Darts ( Giga have huge Torper Rate So Bring Enough Darts)

7)Food Level will zero so you can tame instant

8) Enjoy your Beast

P.S:-( If you don't have enough levels to make Giga Saddle Complete Strong Cave You can get ascendant giga Saddle)