When I first started magic, it was the end of the release of Dragon's Maze and a new set was on the horizon. I went to my first prelease for Theros. That night I fell in love with the game, the community, and especially this set. I didn't get far in the tournament, but that didn't matter to me. I got a free t-shirt and had a great night with strangers. If I remember correctly I played with the Green release kit, even though more than half of the store wanted to do Black. I still have and play the Bow of Nylea I pulled that night. This cube is a love letter to my first moments in Magic, my favorite plane, and my favorite mechanics still. The cube was designed with what plays within the Theros mechanics.
Heroic - A wonderful representation of the Greek and Roman inspired heroes. Target your creature with a spell, gain an effect. When pondering design steps, it's hard not to believe this was the first mechanic the team came up with and designed other mechanics around them.
Bestow - A mechanic that deserves a come back in standard, these have become unique and key pieces in enchantment decks. Based on another mechanic in the set, I believe this must have been the second design mechanic, but that's just a guess.
Devotion - This was the most flavorful mechanic, appearing on all of the God creature cards to turn them from an enchantment to a creature. It was a goal to reach to gain a great reward, simply for building your board state. Some people would say it's boring, but to the new player it's a great dip into the strategy of the game.
Strive - This mechanic feels like it falls short, only because it's a copy mechanic that costs more mana than it should. In today's meta, they're not desirable, except in niche deckstyles. Because of this and it's lack of ties to other effects other than Heroic, I believe it to be the third mechanic designed. Possibly fourth, when considering the next mechanic.
Constellation - It's the cream of the crop as far as effects. Simple, but brilliant, being brought back in future sets under different names or as itself. I believe it was put into the second set, but maybe designed early in the process.
Inspired - Not my favorite mechanic, but I understand what they were attempting to do. Heroic created a very aggro environment, having a pay off for risking your creatures sounds great in theory. However, it often costed 3+ mana for an average effect. Later in the game's history, this mechanic will find a welcome home in Vehicle decks.