For reference, Bloodlust/Heroism increases haste of THE GROUP (e.g. raid group 2, not the whole raid) by 30% for 40 seconds. Spell had a 10-minute cooldown (which didn't reset after a wipe) but there was no exhaustion debuff.
Raid members could have their group number switched by a raid lead/assistant mid-fight. (I'll call this hot-swapping.) In practice this meant the four people that benefitted the most from heroism/bloodlust would be in a group and then different shamans would be hot-swapped in to cast heroism/bloodlust. This was also at "the expense" of other raiders who if they weren't one of those 4 people wouldn't receive the buff ever.
In BC only shamans had Bloodlust/Heroism.
Drums, a leatherworking item, increased the haste of the group (e.g. group 4) by 80 for seconds. This is roughly 5% haste and again had no debuff associated with it.
Bloodlust/Heroism and drums stacked.
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My personal take is they should remove hot-swapping players mid-fight. I just don't think opening the Raid UI mid-fight is compelling gameplay.
It also adds guild drama for no real purpose. For example, a raid team with 4 players that get perma-bloodlust are always going to top the meters Especially because other players are Never going to get it. This tends to skew people's perceptions because what was maybe a 10% difference in DPS is magnified in to a huge one. Then when loot drops there's a subconscious bias to giving it to the "top" DPS making things even MORE skewed.
Plus there may be technical reasons that groups can't be swapped mid-fight now since that's the way the game has been coded the last 10 years.
I would be ok if hero worked the way it does on retail but it'd have huge implications in choosing which class to play if they do mess with it. Although if they don't change it you're going to see WAY more shamans in BC classic than we ever did during the actual thing.