For example, if you're instructed to draw two cards and you replace the first draw with a dredge ability, another card with a dredge ability (including one that was milled by the first dredge ability) may be used to replace the second draw
Heres a quick reference table for you on the minimum and maximum number of cards for each format
While this would require your opponents to be drawing all the time, thankfully, thats hardly uncommon in Commander
Leonin Arbiter is good, but you have at least five fetch lands where paying 1 life and then an additional to search for a land when you can play Rampant Growth for the same function doesn't make a lotta sense
Fortunately, almost every shop Ive worked with has been more than willing to order cards they dont have for you if asked, and that can be a lifesaver if you need a knowledgeable go-between you can trust to order online for you
The card it reminds me of the most is Monastery Mentor, only having flash makes it more versatile