You get 200 mana, and the depletion is 0.15 mana per 50 milliseconds (i.e. 3 mana per second) multiplied by a self.afterlifeDeaths counter for the player, which resets to 1 upon first afterlife entry of the round and increases by 1 every time you enter afterlife via downing (aside from first afterlife of the round). Keep in mind that some events can also deplete mana, as follows:

• 1 mana per shock
• 0.3 mana per 50 milliseconds while in the air (equivalent to 6 mana per second)
• 10 mana per hit by enemies

So, first afterlife of the round is always normal depletion, subsequent afterlives’ depletion being the same as the previous afterlife or being faster depends on if the current afterlife was entered by downing or not. First down after first afterlife causes the depletion to go twice as fast, and second down causes it to go three times as fast.