Originally Posted by LastSensei

It's available as soon as you unlock the Kitchen by advancing in World Map. But afaik, cookies increases exp gained by 30%. I dunno how you gain eggs faster that way.

They also increase drop chance slightly

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By the way, do u think the battle buffs, like increase damage for 3 turns, are useful? Haven't tested much with that since an attack ability seemed better.
Also they only apply to the caster, right? (Except maybe when written otherwise)