Amethyst Thorns

Cruelty (You may reduce this spell's mana value equal to the last amount of life lost by your opponent this turn.)
Amethyst Thorns deals 1 damage to any target.
Necromancy 1 (You may exile a creature from your graveyard in addition to its other costs to cast this card from your graveyard. Then exile it.)
A most basic faren spell, but quite ubiquitous.