Could you please tell me what kind of strategy do you have in mind around that card. I have it, but I have no idea what to do with it. It doesn't seem like "rare" quality card to me, but then again there's The weight of a legacy so I could be wrong about understanding what "rare" quality of cards is. 
It's definitely a rare-worthy card. I think you're misinterpreting the difference between rarity and power level. Rare cards don't have to be powerful (this is great example), but they have to feel rare, do something impressive, interesting or flashy. This card does something hardly any other card in the game does (allows the Shadow players to decide the order of skirmishes) which definitely makes it feel rare, but also makes it not very good. I've often thought about that card while playing my
![Rohan [Rohan]](https://lotrtcgdb.com/forums/Smileys/classic/rohan.png)
decks and it turns out that in a lot of cases the order you fight is the difference between life and death. But it's still rare-worthy.
More to the point, there also need to be powerful commons and uncommons, some more powerful than many rares. For example,
Captured by the Ring - arguably the best [gollum] card ever printed, at common. It doesn't do anything off-the-wall or flashy, it needs to be common because it's an important part of any deck that needs Gollum, and so it fits nicely at common, while still (arguably) outstripping
Promise Keeping and
They Stole It in power!
As for the actual rules issue, I'm pretty sure that whenever a card says "Discard during" or "Discard in" the regroup phase, it means at the start of the regroup phase.
Thranduil