The aim of the game is simple: Create a card that would be a good fit for a Commander deck helmed by the legend that the previous poster suggested, then suggest one of your own. Of course, the card can't have a color identity that would prohibit it from being used in that deck; and planeswalkers-that-can-be-commanders are okay to be suggest too.
Whenever a dragon you control enters the battlefield it gains haste and double strike until the end of turn.
Whevever a dragon you control deals combat damage you may add RG to your mana pool.
Herald of Pinnacles1WRB
Creature - Human Cleric
When ~ enters the battlefield, search your library for a Demon,Angel, or Dragon creature card. Reveal it and put it into your hand. Shuffle your library afterwards.
Creature - Angel
When Banetamer Angel enters the battlefield, search your library for a Demon or Dragon card, reveal it, and put it into your hand, then shuffle your library.
Whenever a Demon or Dragon creature enters the battlefield, you may put a +1/+1 counter on that creature. If you do, put three +1/+1 counters on Banetamer Angel and you gain 3 life.
When Saproling Onslaught enters the battlefield, put a 1/1 green Saproling creature token onto the battlefield.
At the beginning of the end step, put two 1/1 green Saproling creature tokens onto the battlefield for each Saproling that died this turn.
Artifact Creature- Construct
When Rummaging Scrapling enters the battlefield, you may search your library for an artifact card, and put it into your graveyard, then shuffle your library.
Enchantment - Aura
Enchanted creature gets +2/+2 for each card in your hand and for each enchantment you control.
Enchantment Barrier - Whenever damage is prevented by a spell or ability you control, if Hidden Hierophants is an enchantment, Hidden Hierophants becomes a 3/3 Druid creature with vigilance.
Whenever a creature enters the battlefield from your graveyard put a +1/+1 counter in it.
Here's a bonus card because I had the absolutely perfect card for Obzedat both flavorfully and mechanically but I couldn't post it at the time and by the time i could it had been done.
Whenever a creature enters the battlefield under your control you may exile it then return it to the battlefield under your control.
If a creature would enter the battlefield under an opponent's control instead exile it then put into play under its owners control at the beginning of your next endstep. "Why would the Ghost Council want the districts redrawn like this? Those spooks are up to something I just don't know what. Where in Azor's name is Jace?" - Lavinia
Creature- Plant Elf
When Rot Farmer enters the battlefield , you may sacrifice up to two lands. If you do, search your library for that many basic land cards, and put them onto the battlefield tapped, then shuffle your library.