Spell cancelled
I was playing a card with spree, and I paid the +3 to create a copy of target creature or artifact I controlled. I then also paid +2 to draw two cards and discard a card. The game then asked me to select a target creature or artifact, so I selected my geyser drake. Then, my opponent plays a card that returns my geyser drake to my hand. This should normally just make me unable to target the drake to make a copy, and I would still be able to draw my two cards and discard one. However, instead my geyser drake returned to my hand, and the spell when straight to the graveyard, without triggering at all. I do not know why this happened, but I do know that it should not.
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DAC169#34537 commented
"If the first and/or second modes are chosen, then Three Steps Ahead has one or more targets. If so, and all its targets are illegal as it tries to resolve, Three Steps Ahead won’t resolve and none of its effects will happen. If at least one target is still legal, the spell will resolve and modes with legal targets (and the third mode, if chosen) will have their effects."
TL,DR - if all a spell's targets are illegal when it resolves then it does nothing.