Hey Vain, like RJ said the SERM's (selective estrogen reuptake modulators competitively bind to estrogen receptors. Estrogen hormones themselves will inhibit your own production of testosterone because it is a by product of high testosterone levels so to speak via aromitization of testosterone (aromatase enzyme rate limiting step in this reaction).
I really do not understand the reasoning of using two different SERM's for post cycle, not sure of the benifit since you are essentially adding another compound to do the same thing. I know there is some anecdotal evidence for adding both clomid and nolvadex for example but I have not seen good scientific evidence.
NOW i'm not saying it is not out there, I just havn't seen it. If someone knows of this please link a reference.
Nolvadex is something also called tamoxifen. This is an old drug to treat ESTROGEN RECEPTOR POSITIVE breast cancer. So, the cancer has receptors that bind estrogen and grow from activation of the estrogen receptor. The tamoxifen/nolvadex again competitively binds on the receptor as well and slows growth.
Good way to think of it is like a cast tank in a car. The tank is the estrogen receptor. You can fill it with either gas (the car starts and drives) or water in which case the engine won't start and dont go anywhere.
Or, think of the receptor like a pussy, you can put your dick in it or your finger, or dildo or cucumber, carrot, beer bottle etc etc. Your dick might get her pregnant which is a problem, the dildo/finger veggie etc is just fun.
In your case i might should have used the chocolate starfish as the example, you know the ole
brown eye