Easy Bro, at low dosages Nolva act ONLY as a SERM do not confuse SERMs (like nolva) and IAs ( 3 top: Letrozole, Exemestane and Anastrozole), similar to IA in objetives (BUT NOT THE SAME, i.e. fighting for attaching to your estro), fighting for receptors against estrogens and consecuently blocking them to act and avoiding well known undesirable effects. It is important to remark that IAs act different from SERMs do, IAs cut the problem from its root avoiding having strogen receptors, but as we know this could be bad cause we need certain strogen levels in order to mantain our inm. system and, of course, droids need also a certain balance of blood strogen to work correctly, thats why it is very important to control IAs dosage and that is because we use to take adex EOD at low dosages.

All above is being ON, talking about PCT is different, Nolva at doses from 10 to 20 mgs ED acts as SERM (normally @ 10 mgs ED), when we are talking about PCT we need to consider that Nolva at dosages higher than 10, like 20, 30 or 40 mgs ED (common dosage at PCT) acts like SERMs attaching to your estrogen receptors and helping you to raise your endo testo levels, specially at 40 mgs ED. That is the reason cause many people only uses Nolva in their PCT, cause many times is enough to restart your test levels (specially if you have not use strong HPTA sup. drois like Deca or Trembo). It is a good way of making a good PCT and avoid Clomid sides (remeber that many people has suffer serious sides with clomid).

The main reason of avoid using Adex and Tamox is simply, adex can not be used with Tamox, they interfere each other, many researchs have demonstrate that Tamox decrease seriously Adex results (about 33% of decrease) and it should be like throwing away your money... Exemestane is a bit different as does not interfere with tamox and can be used together, the key is find the balance between the SERM used and IA (prov+tamox & xtane).

I copy my reply from another post similar to this bro, hope this help

I clomid is only for recovery of your HPTA axis while tamox has more uses (acts as SERM as antiestrogen and can help at recovering in PCT both thats why you can use during cycle and during PCT).

Using or not Clomid depends from eache one and of course the droids used bro, when you use strong HTPA suppresors is better to have clomid near for your PCT, is worth to.