What's included in the product? Having Arimistane in it does not raise confidence towards the product.
First of all use only 1 SARM, if you haven't used them before. If something starts to go sideways, you don't know what compound in the stack is giving you the problems. And you don't really need more, than one effectively dosed SARM, at least for your first run with them.
Definitely have and do a PCT. Tamoxifen, Clomid, Enclomiphene all good options. Make sure to have the SERM on hand before starting any cycle.
Using something that converts to at least estro and preferably to test as well would be advised, like the above mentioned 4-Andro or Dermacrine. Could possibly be ok without, but could also feel like an ass during the run.
Why would Anavar solo be any more pointless, than a SARM solo or a SARM stack?
A lot of bad quality SARM products out there. Many do not contain what's on the label. This Mass Stack may do, I'm not familiar with it. If you're in the US, then MAResearch is one tried, trusted and liked source for SARMs and SERMs (and peptides). @Smont has a discount code for you, if you'd like to give them a go.