Are the slayers increasing the spawn rate this time? In past events, getting some number of EP increased your spawn rate as did having R and SR slayers. I didn't see any notifications of either of those.

If you grind it out, you can get SEGs. It just takes a LOT of elixirs. I've burned through over 200 elixirs so far to get 156 SEGs (a LOT were shared, but I'm producing about 10-15%)