You lose life equal to that spell's mana value
Like most Pokmon cards, the value of Pikachu 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 (Crown Zenith)
The Reaper, King No More Theres a mild irony in how The Reaper, King No More is likely a more consistent, powerful commander than Reaper King
With Great Power is now the far more ominous Chosen by Valgavoth, and Spider Man's Origin is now A Most Helpful Weaver, which is not only cute but actually fits the effects of the card way better
Ritual of Soot isnt perfect, most notably not being able to destroy Vine Mare or Nullhide Ferox, but its still more reliable than Phyrexian Scriptures