All they did with the annie charges is standardize it so its like every other champion.
Think nunu, who melee's 7 times then has a free spell. After the 7 hits his buff says he has a free spell. For annie, now after 4 spells it'll says her next spell will stun. This is in place of her never having a buff that says her next spell stuns, but her 5th spell stunning.
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PhoneYoshi