Your spot on Mash.
AI's work by changing the T:E ratio, by lowering estrogen, the body will increase endogenous testosterone. It should be noted that AI's arnt always needed during PCT, if estrogen has been kept in normal ranges during the cycle.
Lowering estrogen too much can bring its own sides. Like, loss of labido, sore joints, bad cholesterol and damaging the CNS. This is why I never suggest using AI's during PCT, if ones been used on cycle. (One could also warrant an AI's use during PCT to avoid an estrogenic rebound too though.)
SERM's act by inhibiting estrogen at the hypothalamus and Clomid and Torm seem to be the most active here, hence their first choice in many PCT protocols now.
A simple PCT of a combination of SERM's will usually work and well at that.
I'd suggest Torm, Clomid and Tamoxifen to be your first port of call during PCT.
The doses would be:
Clomid 25-50mg/ED
Tamox 20mg/ED
Torm 60-120mg/ED
All ran until recovered (bloodworks needed) or around 5-6 weeks.