<p>No, you can't. Part of the process of casting a spell is checking whether it's legal to cast:</p>
<blockquote>
<p>601.2e The game checks to see if the proposed spell can legally be cast. If the proposed spell is
illegal, the game returns to the moment before the casting of that spell was proposed (see rule
725, “Handling Illegal Actions”).</p>
</blockquote>
<p>If any chosen target is illegal, the game reverts to its state right before you started casting Thoughtseize, so Prowess never triggers.</p>

CC BY-SA 4.0
2020-08-29T15:44:28.550Z
You could, of course, cast Thoughtseize targeting yourself, but that seems suboptimal unless the prowess trigger will immediately win you the game.
Arcanist Lupus
CC BY-SA 4.0
2021-09-16T13:30:07.320Z
@Caleth A) thoughtseize isn't a search effect,  so fail to find doesn't apply, B) even if it did, you would still lose 2 life and reveal your hand, which is still suboptimal though not as bad.
Arcanist Lupus
CC BY-SA 4.0
2020-08-29T05:35:25.507Z
2021-09-15T17:49:27.120Z
2021-09-15T17:49:27.120Z
Arthur
<p>Casting a spell requires a legal target which a player with hexproof is not (according to the comprehensive rules):</p>
<blockquote>
<p>702.11c “Hexproof” on a player means “You can’t be the target of spells or abilities your opponents control.”</p>
</blockquote>
<p>Your example would work if the opponent becomes an illegal target while Thoughtseize is on the stack.</p>

CC BY-SA 4.0
2020-08-29T05:37:28.110Z
2020-08-29T23:34:02.150Z
2020-08-29T23:34:02.150Z
Fjedsen
<p>Whether the targets of a spell are legal is checked both at the casting and at the resolution. &quot;Fizzle&quot; refers to when a spell's targets are valid at the time of casting, but become invalid by the time of the resolution. A spell whose targets are not valid at the time of casting does not &quot;fizzle&quot;, it simply is not cast at all.</p>

CC BY-SA 4.0
2021-09-15T21:17:26.193Z
2021-09-15T21:17:26.193Z
Acccumulation
<p>Let's say an opponent has hexproof due to <a href="https://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=466780" rel="nofollow noreferrer">Leyline of Sanctity</a>.  Can I still cast a spell like <a href="https://gatherer.wizards.com/pages/card/Details.aspx?multiverseid=438676" rel="nofollow noreferrer">Thoughtseize</a> against them, just to let it fizzle and trigger prowess?</p>

<magic-the-gathering>
Can I target a hexproof opponent in order to trigger prowess?
Derek Chiang
# Can I target a hexproof opponent in order to trigger prowess?

(Asked by: username_0 on 2020-08-29)

Let's say an opponent has hexproof due to [Leyline of Sanctity](https://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=466780). Can I still cast a spell like [Thoughtseize](https://gatherer.wizards.com/pages/card/Details.aspx?multiverseid=438676) against them, just to let it fizzle and trigger prowess?

**Tags:** magic-the-gathering


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## 3 answers

### Answer by username_1 on 2020-08-29. Score: 5

No, you can't. Part of the process of casting a spell is checking whether it's legal to cast:

> 601.2e The game checks to see if the proposed spell can legally be cast. If the proposed spell is
> illegal, the game returns to the moment before the casting of that spell was proposed (see rule
> 725, “Handling Illegal Actions”).

If any chosen target is illegal, the game reverts to its state right before you started casting Thoughtseize, so Prowess never triggers.

> **Comments:**
> **username_2**: You could, of course, cast Thoughtseize targeting yourself, but that seems suboptimal unless the prowess trigger will immediately win you the game.  
> **username_2**: @Caleth A) thoughtseize isn't a search effect,  so fail to find doesn't apply, B) even if it did, you would still lose 2 life and reveal your hand, which is still suboptimal though not as bad.  

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### Answer by username_3 on 2020-08-29. Score: 2

Casting a spell requires a legal target which a player with hexproof is not (according to the comprehensive rules):

> 702.11c “Hexproof” on a player means “You can’t be the target of spells or abilities your opponents control.”

Your example would work if the opponent becomes an illegal target while Thoughtseize is on the stack.


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### Answer by username_4 on 2021-09-15. Score: 0

Whether the targets of a spell are legal is checked both at the casting and at the resolution. "Fizzle" refers to when a spell's targets are valid at the time of casting, but become invalid by the time of the resolution. A spell whose targets are not valid at the time of casting does not "fizzle", it simply is not cast at all.


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