Flowey is an excellent card, especially for its price, who's main ability is to be placed back into the deck with +3 ATK added onto its stats every time it dies. Under most circumstances, it makes this card impossible to kill. The only exceptions are:
- Kill it while being Silenced by using cards like Nacarat Jester.
- Transform it using Snow Storm.
- Remove it from the board with Dimensional Box or the Load spell from Omega Flowey.
However, he has Haste the first time he is summoned, so a good idea is to place Flowey and make it attack a monster with 6 or more ATK, killing itself right away to avoid the chance of it being removed.
Adding Taunt to it with Protection (in Patience) or Glad Dummy (in general) is also a good idea. Another common strategy is to swap its stats with Madjick, making it easy to kill tough opponents, getting killed itself and able to come back with an already high ATK stat of 8. It's also useful in decks that rely on heavy drawing, such as Bravery and Integrity, as it prevents the user from running out of cards and taking empty deck draw damage.