His value scales with game length
As you cast a spell or activate an ability with one or more Phyrexian mana symbols in its cost, you choose how to pay for each Phyrexian mana symbol at the same time you would choose modes or choose a value for X
Third, it still costs mana and time (or life, in the case of Street Wraith) to use
You can do this by attacking with two or more creatures, sure, but more commonly youll do this by just dropping your load of dice on the board through other means or just saying nah and drawing 25 like the Simic player we both know you are
(Each booster pack contains 10 randomly inserted game cards.)
Alongside this, when being tempted by the ring, Sauron, the Dark Lord offers a potentially incredible amount of card draw