Olivia's Attendants is an expensive card, costing a whopping six mana unless you have Strefan and two Blood tokens already available, and then they can be dropped onto the battlefield super-fast
In addition to this, a big part of the reason these cards were so popular was because the mana in that Standard format was quite bad, to the extent that you were pretty close to wanting Attune with Aether in your decks even before the energy bonus, but once you have the energy bonus you might as well play Harnessed Lightning, which means you may as well play Rogue Refiner to power up your kill spell, and so on
The most notable high-value reprint is Toxic Deluge, a notorious board wipe spell that, at the cost of some life, can easily demolish the entire board and even take out indestructible creatures with its -X/-X effect
Really just a mana rock, but also built in exile to play, and you could do things like flicker it and such
They are both 1/1 creatures for one mana that can prevent combat damage by being sacrificed
All you need is to survive one more of your opponents attacks so that you can untap and cast your game-winning spell
