Can i deduct the $850 amt. for my prescription plan? after the 850 is met, then I just have copays

Yes if you paid it out of pocket.  You need to use Deluxe or higher to enter deductions.  

But You can only deduct the amount of unreimbursed Medical Expenses you actually paid over 7.5% of your AGI.  And then all your itemized deductions have to be more than the standard deduction to get any benefit (so you would only be getting the benefit of the amount that puts you over the standard deduction).  And since the Standard Deduction is increased more people will not need to Itemize.

If you pay an out-of-pocket $850 deductible, yes, that would be a medical expense. 

@spoonerbaby1-yah