There are three different variants of the Strain phase 1 Revenant, and all are very easy to assemble. Two of them only require attaching to the base, and the other just needs the two halves of the body joining.
Here are the parts of the three variants -
The two single piece miniatures just require attaching to the base -
The other Revenant just need the two halves gluing together. It's best to attach the feet to the base first - that allows you to get a good contact between the two halves of the body and the left hand which is touching the base -