I would say the key to Uldyssian fight is to slow him down (Big thanks to gaves15 and trnhd94 for this recommendation

). The more slow you have on him the better. I tried him with 25% slow

(Walfang SSU Short War Bow), 37% slow

(crafted Short War Bow), 43% slow

(Lo runeword) and 50% slow

(Lo Xis runeword). All works out just fine. But the time doing him is inverse proportion with the %slow you have.
Before that, I was trying to increase my damage and attack speed so as to kill edyrems faster. That didn't work

. Because no matter how fast I kill those edyrems, they will just be summonned right back up in seconds. The rate that he summons edyrems is so fast that I would only recommend using no slow on him when you need only the experience from edyrems. But of course that will make the sprite limit accumulates faster than having him slow and your game will crash more often.
It seems to me that when he is slow, he summons less edyrems and the sprite limit accummulates slower

, well, you'll get sprite limit in the end, it's just a matter of how much time you have to fight him before that happens. When that does happen, I would go back to town for 20 seconds to let things calm down (Thanks TS_Mordor_ for this wonderful suggestion

). It seems that the edyrems and he himself will stop whatever they are doing if you are not in the room for a while, they will be standing still, wondering about God's existence and how many votes Trump gonna have in this election. We are not gonna let that happen are we.
