along with arimidex IF NEEDED .
Thank god, finally someone thinking this through. I am glad to hear you have it on hand, but I am also glad to hear that you will be using it only if it becomes necessary. I am assuming you are doing so due to AIs negative impact on HDL and over all HDL:LDL ratios.
As for on cycle supplements, liver support never hurts (though an absolute must if orals are being used). I wouldn't go with just milk thistle alone, rather product with a good reputation and a variety of ingredients, such as Liv52. Also AIsports life support could be useful to run throughout your cycle. Omega-3s should be taken even when not on cycle, however avoid Omega-6s as most people already over consume those.
I would keep the multivitamin, add liver support such as liv52, add ALA, possibly AIsports life support, and definitely add joint support (as aas tends to wreak havoc on joints due to fluctuations in hormones, namely oestrogen).
I would also avoid anything that puts stress on the liver during the duration of your cycle. Drinking is an obvious, but there are other things that people tend to over look. CoQ10, forever, has been shown to elevate liver enzymes in some people and as such should be avoided while on cycle (especially when orals are run). Also acetaminophen, note that this means no cold medicine containing it either!
On a side note: anti-inflammatory drugs actually hinder protein synthesis in muscles, and as such growth and recovery. If you have sore joints it is better to change your routine structure than medicate, namely drop weight and up reps.
Best,
Parker.
PS: It may be helpful to stop using pre-workout (if you use it on cycle) a few weeks out from the end of your cycle, this way you desensitize yourself to the stimulants so they have more of a kick when you need it during your PCT.