Spriggian and Totems Why both?

Kind of might play a Primalist Shaman / Druid Spriggan build, but what why do you need both? I’m not good at those two.. Can someone explain what the spriggan thing does or whatever?

Sprigging form allows summon healing totems which can be modified in the spriggan tree to use the thorn totem skill + you can get 9 totems (thorn totem skill only allows 5-6, in spriggan form you can get up to 9. and the thorn tottems heal you and your allies.)