So:10 points, Recycle metamorphosis for 2 points, 12 points left
2 points, buy down stoneskin ability cost from 6 to 5, 10 points left
2 points, buy down stoneskin ability cost from 5 to 4, 8 points left
2 points, buy down stoneskin ability cost from 4 to 3, 6 points left
1 point, Body armor trait, Counts as [b]armored[/b] for +3 defense, 5 points left
1 point, Gas mask Trait, Immune to [b]stunned[b] effect, 4 points left
2 points, Brick blood, Immune to [b]burning[b] effect, 2 points left. 

Considering to buy "gopher hole" to have an attack, or raise his attack now and get gopher hole later with a higher attack.