An easy way to predict how much damage will be done by a certain turn is to use this formula.
((2 ^ Turn #) * 200) - 200 = Damage to LP
To simply it, the total damage you receive throughout the duel with this card is the damage the next turn will bring - 200. So if next turn you will receive 800 LP of damage then you currently lost 800-200 (or 600) LP of damage.
On the 6th turn this card can deliver 12600 points of damage, meaning that if the enemy has not used any Life Point gaining effects then they will lose in 6 turns. This is almost as fast as the Spirit Message cards and 2 turns faster than the Wave-Motion Cannon.
In a duel where you have a 40 card deck, you can activate 34 standby phases after activating this card on your first turn. This means the most amount of damage this card can do is 3,435,973,836,600. or 3.4 trillion. With 3 of these cards it's 10,307,921,509,800.
In a 80 card duel it is at least 3.77789 Quadrillion or 3,777,890,000,000,000,000,000,000. With 3 Dark Snakes it's 11.3337 Quadrillion.
Some cards like Outstanding Dog Marron which can prevent you from getting a Deck Out can allow you to have theoretically infinite turns and thus, infinite damage via Dark Snake Syndrome.
You can combine this card with D/D/D Oracle King d'Arc to ensure that even if your opponent destroys it before it can defeat them, it will still cause you to gain an obscene LP advantage by both damaging them and causing you to achieve potentially quadruple digit or better LP gain before they can get rid of it, especially if you run multiple copies at once.