1. As mentioned in this thread here https://forum.nostalrius.org/viewtopic.php?f=40&t=3554 the user expressed the inability to summon a player while BOTH of you are in the instance/raid, have them hearth, and return back to the respective instance/raid before the summon has expired. Just clearing that up because the thread has caused some confusion. http://www.wowwiki.com/Ritual_of_Summoning
Players can target themselves as the summoning target in order to quickly hearth, repair, and then return to the spot where the ritual was performed. This works inside of an instance as long as the warlock meets the requirements for the instance.
Also taken from https://web.archive.org/web/20070312154 ... _Summoning
Limitations
A Warlock (with two party members standing with the Warlock to assist - this always applies except when using a Meeting Stone), can summon from anywhere in Azeroth and all but one zone in Outland to wherever the Warlock is in Outland or Azeroth. A Warlock can also summon any character from anywhere in the specific instance he is in to himself.
A Warlock cannot summon a person from the world map to the inside of an instance or summon a person out of an instance to the world map.
This was a link supposedly from the time of TBC. If by then this type of summon>hearth>accept action wasn't listed as a limitation, I'm inclined to believe that it was indeed possible, technically it still falls under the limitation of "A Warlock cannot summon a person from the world map to the inside of an instance". Waiting for more clarification on this.
2. Summoning a player 5 or more levels below the warlock while both players are in an instance will result in an error message saying something along the line of "Target is too low level". I was summoning a Lvl 42 player that had entered ZF (I was Lv 47). This player was clearly within the minimum instance requirements as they were indeed inside it, yet I was unable to summon them. If the difference is fewer than 4 levels, I am able to summon inside an instance. Have not tried doing this with high level targets yet. In addition, this kind of summoning was not listed as a limitation in the previous source.
http://wowmb.net/index.php?page=Ritual_of_Summoning
Can I summon a player of any level?
Yes, there is no level limitation on the person you are summoning.
3. Similar to what's mentioned in this thread https://forum.nostalrius.org/viewtopic.php?f=40&t=11627, two warlocks cannot simultaneously drain life on a single target. Using this ability while one warlock is draining will cancel their spell. However, two warlocks using Drain Soul won't experience any issues.
https://www.youtube.com/watch?v=3VTwW5mvm-s 0:53 (for all I know this could be on a private server and Nostalrius really does have it right.)
4. Curses will be knocked off by lower priority debuffs, even if the warlock has both Corruption and a curse up on the target (don't flame me these are only 5 man observations). So far I've seen this with Curse of Agony. If the assumptions in this thread are correct https://forum.nostalrius.org/viewtopic.php?f=40&t=1044 then should not corruption be replaced instead? Perhaps I'm mistaken about this and it may have something to due with the duration of corruption at the time a new debuff was introduced, that somehow makes it (Corruption) a higher priority debuff temporarily.
I apologise in advance for any inaccuracies, feel free to point them out and I'll remove them from this thread. Everything is of course up for debate.