Titan shifting

For ten rounds you become a Titan making your size giant and your strength modifier becomes maxed. It also makes your intelligence -1. Your movement doubles except for flying speeds Witch get split. No weapons can be used in this state but your unarmed attack is x3 (+3d4) your base unarmed. Your health doubles your max. For ten minutes after this spell ends no spells can be cast. You can use this once every 2 long rests. (Note: if its your first time using this spell at the beginning of the spell you have to roll (int dc:17) if you succeed the spell  continues like normal. If you fail your Titian instincts take over and you view everyone on the battlefield as an enemy.) your AC becomes 20 and no spells can be cast while in this state.