Timbermare was created as a tribute to pro player Jamie Wakefield's wife Marilyn (nicknamed "Lovely Mare"), who died of ovarian cancer. Keep in mind that Magic sets are designed about a year in advance, and Planar Chaos came out about a year after her death, meaning that the card was designed almost immediately after the tragedy. The full story.
Being the creator of a multi-billion dollar game allows Richard Garfield to create some nifty cards. But there's more! The art of the first card was left undocumented by Garfield's request, which was for the longest time honored by the entire Internet (but can now be seen here◊). The second card speaks for itself, and if you don't get the art for the third, consider why the artist put four plates on the table.
When Elspeth has been cast out as a scapegoat for Xenagos' ascension and turned against by seemingly all of Theros, including Heliod, Ajani comes looking for her and becomes her companion on the quest to slay Xenagos, along with the leonin of Theros. Cemented by Solidarity of Heroes.
Even amidst the Downer Ending of Godsend, there's heartwarming to be found. Elspeth's breath slowed as he took her beyond the boundary of Nykthos, Shrine to Nyx and laid her upon the bare earth. He wouldn't let her die at the feet of the gods. Even in Elspeth's last moments, Ajani is still there for her.
Reviving Melody, which depicts about a woman rescuing her husband from the Underworld, telling him "Listen to my song, and you need never forge a golden mask to return to me."note In the plane of Theros, those trapped in the Underworld can escape by forging a golden mask, at the cost of the memories of their former lives.