Hidetsugu's Second Rite
Hidetsugu's Second Rite is the least fun way to lose a game in standard. There are no other cards that can deal 10 damage or outright end a game when you're at 10 health, for so little mana. MAKE IT A SORCERY
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Rezzahan#77802
commented
Getting an opponent to exactly 10 life is quite the undertaking, and the effort to do so makes HSR a very fringe card, that usually does nothing.
Also, that card is old, printed in the original Kamigawa block, and will not be changed whatsoever for paper Magic. If you are into Alchemy and Historic, a rebalancing is possible, but most likely that would only be to make it more powerful, not less. Because it is not very powerful. Ultimately, that card is of no concern in regards to balancing issues.