Like most Magic: The Gathering cards, the value of The Tenth Doctor depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Doctor Who)
Baxas art in Magic, and this unholy combination has led to some fantastically horrifying scenes, like the one depicted on Swarmyard
Building Value Over Time Rarity-based collecting can pay off but patience is key
Ichthyomorphosis Did It Need To Be So Complicated
Overrun is not quite as flexible as the Cloud and requires you to have a decent dork count and so I rate it less highly but it is a similar style of card that in the power levels of cube you need to employ to be able to get you there against a lot of decks
You only go down one mana for the turn, so you can probably even cast another spell