They serve to give your side of the board tempo by allowing your creatures to attack (removing defenders), giving you more time to set up the board (removing attackers/expensive creatures), and allow for combat tricks (saving your creatures after damage is on the stack
As theyre uninkable, that can turn into them being quite useless in your hand for a few turns
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If the target creature is a legal target but isn't destroyed, most likely because it has indestructible, you'll still draw a card if another creature died this turn
Instead of loading up your own creatures, you aim your auras at your opponents permanents and if their mana value isnt higher than the aura's, you just steal them
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