- all expansion rares are placed in locations that are neutral, meaning its not affected by phasing. However, it can be dragged into a phased zone, so while NPCScan can detect it even while in phased, you cant target it if its not there. When NPCscan / silverdragon detects a rare, it discovers the mob ID in the cache..however the targetting box rely on the nameplate or name of the mob (meaning the mob must be visible).
- ever since the introduction of woltk, the graphics engine has been a bit funny. mobs now appear when you within the max viewable setting that your graphics is set to or can do. this gives the "false" sudden spawn experience like you land and suddenly the mobs appear or is picked up by NPCscan / silverdragon, i have alot of experience with this because sometimes or i used to have issues with network and graphics lag. one example i can give is numaroc, before woltk, numaroc can be seen from far away and will fade like normal when go out of range regardless of the height or angle i look at him, but in woltk he can suddenly disappear when i change angle or height. i'm also mentioning this because terrorpene, i know terrorpene has only one spawn spot and from there he walks all around the lava pools till his killed or tamed. i've seen someone else post this before, but i also seen other people say he can spawn from the other locations, which i'm doubtful (i've tamed terrorpene on different hunters in different servers at different times and each time is the location, i just camp at his spawn spot).
sharing timer issue... i believe a majority of expansion rares dont share timer, they might seem to share a timer because we hardly see them exist together at any given time in the zone, but i think this is because blizzard staggers their initial spawn time. they might eventually meet up, which explains why some people have seen more than one rare up at a time, like in basin. but some mobs do seem to share a timer like time lost proto drake with vrygossa and aeonaxx with xariona, meaning so long as one mob is alive on the map... the other wont spawn.
randomness is important. why? because it gives different players a chance at the mob. i'm currently in the asian region and i'm playing on a north american server, so my time is really different from the major population of the server. if there is no randomness, i would never have been able tamed any rares. this randomness allows for the rare to spawn at different time of the day, however it does take time (and luck) for the spawn range to occur within the time your playing. i figure this out when i was camping for karoma. so if you've been looking for the rare "randomly" at the same time range, like some players say "early in the morning and when i come home" and found nothing, chances are the rare spawn range has not reached the time range of you playing yet.
one last thing, due to randomness and luck, and also because of the changes in the new "tame" ability, where its shorter than before, it is possible that a rare could have tamed (in less than a minute) by a random passer-by. I macro my tame ability with a speed potion so that if i ever find any rare i want i would tame it in the fastest time possible...also because i'm paranoid and have "ninja" tame phobia (like other users on the forum i've had my share of heartbreaks and awful experience of other players stealing tame or killing the rare while i'm taming). for rares with multiple spawn points you have to factor this as a difficulty too and the difficulty increases when the spawn points are far apart.
back in the old days.... we didnt have npcscan or silverdragon ..... or other addons to help, but today i see it would be very difficult to find a rare without it (phasing, competition, busy traffic areas ...etc). however dont reply just on npcscan or addons, make a spamming /tar macro for the mob you are looking for, doesnt hurt to have a back up
anyways, good luck to all of you hunters out there.... i hope you get what you are looking for. sorry for the long post
i play my hunters on two server, lothar and dawnbringer, so if you are on the same server looking for a specific rare, i might have the times.