encore makes it hard to remove profitably without exile-based interaction
Their existence is the reason a deck like Paradoxical Outcome is so powerful, as they come down for free and immediately tap for mana
Limit Break (FINAL FANTASY VII) If you're a FINAL FANTASY fan, there's a good chance you've interacted with FINAL FANTASY VII and even more likely that you can recognize the game's lead characters, like Cloud

For reference my current Legacy Tron decklist looks something like this: Tron - Legacy | Jeff Hoogland Creatures (5) 1 Kozilek, the Great Distortion 1 Ulamog, the Ceaseless Hunger 3 Wurmcoil Engine Planeswalkers (6) 2 Ugin, the Spirit Dragon 4 Karn Liberated Instants (2) 2 Crop Rotation Sorceries (10) 2 Collective Brutality 4 Ancient Stirrings 4 Sylvan Scrying Artifacts (17) 2 Relic of Progenitus 3 Oblivion Stone 4 Chromatic Sphere 4 Chromatic Star 4 Expedition Map Lands (20) 1 Forest 1 Eye of Ugin 1 Karakas 1 Urborg, Tomb of Yawgmoth 4 Bayou 4 Urza's Mine 4 Urza's Power Plant 4 Urza's Tower Sideboard (15) 1 Bojuka Bog 2 Collective Brutality 1 Oblivion Stone 3 Pithing Needle 1 Seal of Primordium 2 Sphere of Resistance 2 Toxic Deluge 1 Walking Ballista 2 Warping Wail While this deck started off as a joke, the more I have played it the more I feel like there might really be something here
Retrieved December 10, 2017
They go into a kind of storage bank, like poison counters and rad counters