Hyper Beam

Description
The reduction in stacks with every use, and will persist until the end of battle.

Strategy and Synergy
Note that the damage reduction will immediately affect the first cast, so in theory, it deals 48 damage per hit, not 50.

Hyperbeam costs 3 mana, deals a maximum of 200 (192 without Spell Power buffs) damage and lowers the spell power every time the spell is cast, making for an impractical, not-so-worthy option to add on your deck.

Without, or , this spell will do more harm than good, especially if taken in with spammable decks such as  or. It does require a setup and using it blindly can greatly decrease your DPS potential very quickly.

Upgrades such as, and  are suitable candidates. The latter two will consume the spell upon cast, with Overload doubling the damage to 100x4 (400, or 392 with the reduction in ) for 3 mana, a fair value. The slighty reduction in spell power won't harm as much if the spell is cast only once and it is always possible to recover the lost amount with a cast of Focus anyway.

Trivia
"TM 15" refers to the Pokémon series, in which in most games, the item in question teaches a Pokémon Hyper Beam.