Hello,
The Resto Druid T8 is currently bugged for Ulduar, it currently only heals 50% of what it should heal.
This change was added later in Wrath, in patch 3.2.2 with this change:
- Druid [Tier-8] Healer 4-Piece Set Bonus: The amount of healing this set bonus grants on the initial cast of Rejuvenation has been reduced by 50%. In addition, this set bonus no longer has strange interactions with Harold’s Rejuvenating Broach.
From reading the blue posts at the time, sadly I cannot link here.
The rationale for this change was that Resto Druids were not switching to T9 because the T8 4 set bonus was too powerful. However if T8 the bonus is now very underpowered and not as it was in the original version. This oversight puts druids at a disadvantage to other healers in this phase and should be corrected to be in line with the pillars of Classic wow.
The change can definitely be made again in T9 to stay in line with the pillars