Another point is the usability of the revival unit. Belinda is better than any event unit we've had this year barring maybe Imelia and Claudia for those without a premium princess. She also comes ready made at only 1 copy. The benefit to players without Yuyu really can't be understated.

Even if you don't explicitly need the black spirits past Wall of Magic, the bonus rubies for completion as well as just new content in maps is great. I know I am very much looking forward to spending a bit of time on new maps this month over some of my mind numbing Phalanx 2 farm. Now we just need some more events with a difficult top end to use our better army on.

As an anecdote, I have a min cost Calliope from perfect combines (CR on every copy used) and have 1 extra Calliope in barracks. ~7 months played. I wasn't gunning for witches in recent events to be sure, but you really run out of use for gold spirits from Phalanx 2 long before you get enough Calliopes for 2 min-cost even if you wanted to play it that way assuming freemium. As a light spender I was lucky (unlucky?) enough to roll two blacks and never get a Yuyu and was just reaching the point where I was held back by not being able to do WoM short of spending SC on buff.

Also thx sora, I got him in the other thread :P