| 25 man IC phase 3 (after first two guys are down) is very difficult imo, the MT damage is absolutely insane (upwards of 50-80k on plate w/o resists & cooldowns after 1-2 deaths), its a DPS race, there is a shit-ton of AOE dmg going on, and if anyone dies it probably means a wipe (boss heals for a good chunk and he does more damage to MT). This is all post nerf as well, in the first few weeks of ulduar it was a joke encounter since there were a million exploits (voidwalker tanking, bubble hearthing tanks, pets taunting right before explodes, etc). I put it in the same league as vezax/yogg+1, since vezax/yogg depends on your entire raid being smart whereas IC is more about very good tanks/healers. I also don't know if its bugged or not, usually he puts that static charge (or whatever its called) on the farthest person out in p2, but we've seen him put it on melee and other people during p3.
Freya+3 is also similar in that the raid damage is heavily ramped up from beams, roots, etc. You can however mitigate some of it by making sure the 3-add phase always has interrupters on storm/water, using raid-wide sacrifice/GS at end of little adds phase, etc.
Either way 25 man hard modes are significantly harder than 10 mans, rusted proto drake is a nice achievement but you have to really bow down at the people who have the 25 man version. The numbers bear it out as well, according to guildox 0.41% of guilds have done 25 man Heroic Glory, and 4% have done 10 man Glory - an order of magnitude difference!! | 