Because he sends all damage back to he who damaged it (sort of like an early take on Stuffy Doll), a lot of people wont attack into it with their larger creatures
Christopher Rush, the painter of iconic things like Black Lotus and Lightning Bolt, has had his signature forged more than a few times in an attempt to maximize value
Thanks to this, characters and creatures that usually dont have the ability to travel between planes - essentially, anyone who isnt a planeswalker - suddenly have the chance to cross over from one plane to another
I suspect if I come to update my cube in a few years with all the cards I have missed in my break it will be quite the novel project
Best of all, if the caster has a Wizard creature, they can choose two modes, getting even more value from Flame of Anor
Its totally banned in modern formats, but if you are just playing with an Alpha/Beta deck (because youre rich apparently) then its allowed