Dyir
First Post
I think that would make the feat a little less terrible, but I think the phrase "using a prepared spell or a spell slot" indicates that the designer intended the "buff spell" to be used up as though the character had cast it. On the other hand, having to use up two spell slots, one of which is higher than normal, just to be able to summon a minion with Bull's Strength or Invisibility already cast on it is a little hard to swallow. Especially since you are also already paying a feat for the privilege.
I have no idea how the OC's DM handles the feat, though. If he agrees with your assessment, then (IMO) you've already begun to enter a gray area that might be considered within "house rules." And, at that point, whether or not swarms can be affected by the "buff spell" granted by that feat is one of taste and game balance, rather than RAW. And, honestly, given how the feat is worded, I think a few house rules would mighty help the feat.
I have no idea how the OC's DM handles the feat, though. If he agrees with your assessment, then (IMO) you've already begun to enter a gray area that might be considered within "house rules." And, at that point, whether or not swarms can be affected by the "buff spell" granted by that feat is one of taste and game balance, rather than RAW. And, honestly, given how the feat is worded, I think a few house rules would mighty help the feat.