I'd love if there were some kind of craftable item you could use on a mob, that killing it would give you a small chance to receive the mob's card. Like Quetzacoatl's Card ability, but FFXIV-ified. It could work on any mob, including bosses. Make it like a 5% success rate.
Want a Twintania card? Buy a stack of 99 for 2k apiece and start grinding T5!
A timesink, a gilsink, and the best FF minigame ever conceived in one package.