I vote Velhart to do the list
I've voted myself to do the list
First of all, none of the 'temporary' Followers (Fiend Slayer, Horned Owl, Warhorse etc.) are killed when they are removed from the game - they are always discarded. I agree that this is as it should be. The only situations in which a Follower can be killed are listed below:
Giant Beetle, Vampire Prince, Vampiric Dragon (if you lose); Cyclops (roll 1-2), Shrine Priest (your choice); Soul Drinker (roll doubles); Narrow Path, Chasm (roll 1-2); Defeating Gladiator or Magus.
If it's left at that, it certainly is a weenie ability. Once face-up, the Enemies aren't going to be visited by anyone who isn't confident of beating them. The Shrine Priest's Follower-killing is voluntary, and Soul Drinker's is obscure. For nearly all games, that only leaves the Narrow Path and Chasm, both of which I personally avoid like the plague. I can't see the Valkyire getting more than 2 or 3 Followers a game if the criterion is this strict.