Since it's not a planeswalker or legend, the questions we need to answer is, "Do we consider Obsidian Fireheart to be epic?" The idea that you can light lands on fire and use them to burn an opponent is sort of epic, but it's a lot like a Curse of the Pierced Heart that costs seven-mana
Add to the fact that this card has vibrant cute artwork that was never released outside of Japan, and it is easy to see why it became a valuable chase card for all regions and collectors
(You expend 4 as you spend your fourth total mana to cast spells during a turn.) You may choose to discard your hand even if your hand contains zero cards
Its seen play in nearly every competitive format, was good in Standard and Pioneer, has seen some potential in Legacy alongside Buried Alive, and was a dominant force in Modern
[443] Anne Allison gave a similar finding: all the children she interviewed knew where Pokmon originated, and "many said that, as a result of Pokmon and other 'cool' Japanese goods, they had developed an interest in Japan
This was wrestled with for a while, and eventually we decided that big fliers in red were okay