It is hard to win eternities from the top50, cuz most decks don't seem to have it and those with it always have only one.
Before when I was doing top50 I would just accept every fight and play through regardless of which deck I was up against. I did manage to win a bunch of rares in one day doing this, but I think I got pretty lucky and there were two farm decks up at that time that I kept going up against. The deck I was using can beat the AI in top50 basically every time, so that is not an issue, but I got tired of the fact that 95% of the decks I was up against didn't have many rares I was interested in. So, I decided to try to just only accept the fights that were to one of two decks: mightyhat (he has a rare farming deck up usually) and cisco (his deck isn't really a rare farming deck it just has a ton of rares in it cuz he has some animate weapon deck in there currently). Since I am near the bottom of the top50 I tried to submit my own score as a farming deck but I couldn't get it to work correctly for some reason (and sadly it matched me up against myself quite often!). Anyway, doing this I won a Pulverizer within about 30 min. I am sure it would normally take longer than this but it does give you a very good opportunity to get a bunch of rares. HOWEVER, I must also warn you my score dropped about 4000 points in 30 minutes cuz i went from having a record of about 1000-400 to 1000-800 in that time span by rejecting 95% of the top50 matchups. I don't really care about my score and I am sure I will fall out of the top50 soon anyway so that was fine with me, but I know you are pretty high up there so you might care more. I just checked and it cost me about 4000 electrum as well.
I guess losing 4000 electrum is such a short period of time is kind of bad, but if you are desperate for some rares it could be a good tradeoff. I actually got a lot less lucky on my rolls when doing this compared to when I just met those decks randomly so it wasn't really worth it to me (except I have no real use for the electrum anyway), but I still was able to get a pulverizer and a couple eagle eyes and a shard or two. It seems like mightyhat's most common cards in that deck are miracle, eagle eye, shard and pulvizer. He has arctic squid and trident in there too be they seem to come up much less often on the spinner.
Ok sorry I didn't mean for this post to be this long, but in short if you are willing to lose the electrum and score, I am pretty confident this is the fastest way to get rares. If you don't want to lose those things you can just fight everyone and I think that is still probably the best way to get pulverizer and some other rares. The deck I use has been winning at least 95% against the top50 AI and is really simple... honestly I have not tried many decks against top50 AI so maybe most decks win that much, and some can probably do it faster, I just happened to find something that worked and wasn't interested enough to figure out the optimal deck. But if someone is interested, it is just Mark Light, 5x upgraded sundial, 16x fire tower, 6x fire lance, 2x fahrenheit, 1x disintegrate. I have them all upgraded, the sundials obviously must be upgraded but other than that I don't think it matters too much. Just save sundials until you are in danger if it is a tough deck and then cast all your bolts once you have enough to kill them (never use a bolt on a creature). Usually I wait til about turn 4-6 to play a sundial and then play one every 2 turns after that. fastest I won was in 5 or 6 turns and you usually always win by the 12th or so. Generally the only way it loses is if someone gets a Trident up before you draw your disintegrate, or to upgraded fire rush decks it probably loses about 10% of the time if you don't get your sundials in time. You can also get mastery about 10-20% of the time if I had to guess the number (if they ever put a weapon up you are guaranteed not to get it, but if they don't and you start playing sundials around turn 2-3 you can often do it). I would not recommend this deck against lvl3 cuz a bunch of them have reflector shields and if someone puts that up you lose (I also would not recommend it for pvp since it is reliant on dumb AI). However I have never seen a top50 deck use a reflector shield so it is ok there.
