First-world problems, but events have an unplayably bad return once you're rare-complete in a fraction of the reward-pack sets. Instead of giving out specific-set rewards that are often worthless, why not have Historic, Timeless, Pioneer, Mix-up draft, and whatever other old-card events give out duplicate-protected "packs" guaranteed to contain a Timeless-legal non-UB rare/mythic (or wildcard) in the rare slot, and random commons/uncommons? Cube packs already use this exact technology for one premium slot and their common/uncommon slots, so it shouldn't be much work, and Grab-bag packs and Grab-bag Mythic packs could also be sold in the store for people who want to try their luck.