If you want to use this to repeatedly recast Lion's Eye Diamond, you'll still need a way to mitigate the five life you pay for each loop, and you'll need a win condition
The Warhammer 40k decks have powerful sagas too, some of which already see substantial play with Tom Bombadil
And then when the special was at $18
Something tells me that the reported multi-month waiting time for PSA grading isn't going down anytime soon.
At four mana, he can sit at the top of your mana curve, and if you manage to drop a haste enabler such as Goblin Warchief, you can start doubling your goblins straight away (which then also have haste to attack the turn they enter)
The gracious recipient will draw some extra cards, though at a cost if they can't keep their hand size under control