These cards can be rarer than most energy cards, as they are usually exclusive to the set that they are released in, with only a few popular ones receiving reprintings, such as Double Colorless Energy
"I thought it was important to represent all the playable characters in the story, but I also wanted your Commander games to feature the infected
During the End Phase of this turn, destroy them, and if you do, take damage equal to those destroyed monsters' ATK
Add to that its artwork (it looks like Raikous furious prehistoric cousin) and youve got one of the coolest Pokmon cards to come out of Temporal Forces
If Phantom Flock would be dealt damage from multiple sources at the same time (say, because it's blocked by multiple creatures), all of the damage is prevented and only one +1/+1 counter is removed