These reprints, such as Yen Sid and the Playful Sorcerer Mickey, will have a unique tentacle design on the bottom of their card
Whenever a creature is destroyed (either from a "destroy" effect or from damage), you may activate the regenerate ability (in this case, sacrificing a creature), tap the creature, and remove it from combat (if it's in combat)
Starting Town, for example, improves the deck's colored mana consistency in archetypes like Jund Roots, Boros Mice, Orzhov Sacrifice, Jeskai Artifacts, Rakdos Aggro, Jund Midrange, Esper Pixie, and more
If Im building that deck, Id rather play the planeswalker version of Xenagos
The latter was especially significant as it actually spoiled the nature of the Brothers War Bonus Sheet ahead of time
Hellkite Tyrant is a jerk, and hes the type of jerk you want on your side of a bar fight, where he pulls out a fist full of sand and throws it in someones eyes, and youre like, Wait, you were just walking about with a pocket full of sand all day? They nod