Without too much effort, the Promised End is a 7 drop, which is fairly achievable for the slow and the ramping decks
If a card is worth less than $3.00, it is considered bulk. Bulk cards are typically not worth selling on their own, since the shipping price radically impacts the percentage you can make on the card
Then, one day, people realized that hey -- this might not be such a bad card
Outside those two requirements, Kaalia needs just a little bit of mana acceleration and a backup plan : Kaalia can be a bit of a monolith commander, with her deck becoming unplayable without her on the board unless you have another way to get your big bad beaters into play without hard-casting them
All the power she collected transforms into a small army of vampire tokens that'll bulk out your board - and synergise nicely with some of our other favorite vampire cards
Since he only cares about the first instance of flipping coins, he wont work well with cards that flip consecutive coins