These kinds of cards always play much better than they look, and I expect that to be the case in Foundations as well
The rarity levels are: Common Common cards make up the bulk of all cards
The graveyard is one of the most common and most powerful themes to build around in MTG , so a card that rewards you every turn for milling it or getting it into the 'yard some other way is always going to retain value
Heidar, Rimewind Master belongs in your snow deck to help you bounce problematic permanents back to your opponents hands, but a mono-blue commander for our snow deck just isnt it
Cloudspire Captain Its hard not to include Cloudspire Captain in your mounts/vehicle deck, especially in an EDH setting
The floodgate ability is probably for the best though, since Spawn is a sizable threat on board and turns into up to ten mana's worth of spells on the way out