<p>For each of the two coins that you flip with <a class="mtg-autocard" target="_blank" rel="noreferrer" href="https://gatherer.wizards.com/Pages/Card/Details.aspx?name=Krak%27s%20Thumb">Krak&#39;s Thumb</a> you have an extra chance to win.</p>
<p>This is not the same as flipping double, and keeping the best 5.</p>
<p>Here is the <a href="https://anydice.com/program/228f4" rel="nofollow noreferrer">anydice code</a> I used to calculate this</p>
<pre><code>output 5 d [highest 1 of 2d2] -5 named &quot;Flips won&quot;
</code></pre>
<div class="s-table-container">
<table class="s-table">
<thead>
<tr>
<th>Dice rolled</th>
<th>Probability to get <em>at least</em> that many</th>
</tr>
</thead>
<tbody>
<tr>
<td>0</td>
<td>100.00%</td>
</tr>
<tr>
<td>1</td>
<td>99.90%</td>
</tr>
<tr>
<td>2</td>
<td>98.44%</td>
</tr>
<tr>
<td>3</td>
<td>89.65%</td>
</tr>
<tr>
<td>4</td>
<td>63.28%</td>
</tr>
<tr>
<td>5</td>
<td>23.73%</td>
</tr>
</tbody>
</table>
</div>
<p>So 23.73% of the time you get to cast your cards for free!</p>

CC BY-SA 4.0
2021-06-05T09:30:19.043Z
2021-06-05T09:30:19.043Z
AncientSwordRage
<p><strong>The probability to win all 5 coin flips with Krark's Thumb is 0.75^5, or 23.7%, up from 3.1% without Krark's Thumb.</strong></p>
<p>Normally, you would have a 50% chance to win a single coin flip. Since multiple coin flips are independent of each other, you can just multiply their probabilities, so you get a (0.5)^5 = 0.031 (3.1%) probability to have 5 coin flips go your way.</p>
<p>Each Krark's Thumb essentially halves the probability of losing a coin flip. For one Thumb, It goes from 50% to 25%, so the chance to win goes to 1 - 0.25 = 0.75. The probability to win 5 such coin flips is (0.75)^5 = 0.237, or 23.7%</p>

CC BY-SA 4.0
2021-06-05T09:55:55.133Z
This is a clever way to do it. I didn't twig the extra thumb halves the failure rate. Much simpler.
AncientSwordRage
CC BY-SA 4.0
2021-06-05T09:45:50.677Z
2021-06-05T14:04:45.710Z
2021-06-05T14:04:45.710Z
Hackworth
<p>The new card <a class="mtg-autocard" target="_blank" rel="noreferrer" href="https://gatherer.wizards.com/Pages/Card/Details.aspx?name=Yusri%2C%20Fortune%27s%20Flame">Yusri, Fortune&#39;s Flame</a> has the clause, that if you win 5 flips off it's attack trigger ability, you can cast any card in your hand, <em>for free!</em>.</p>
<blockquote>
<p>Whenever Yusri, Fortune’s Flame attacks, choose a number between 1 and 5. Flip that many coins. For each flip you win, draw a card. For each flip you lose, Yursi deals 2 damage to you. <strong>If you won five flips this way, you may cast spells from your hand this turn without paying their mana costs.</strong></p>
</blockquote>
<p><sub>emphasis mine</sub></p>
<p>Normally this gives you a 1/32 chance (1 in 2 to the power of 5), but what happens if you have <a class="mtg-autocard" target="_blank" rel="noreferrer" href="https://gatherer.wizards.com/Pages/Card/Details.aspx?name=Krark%27s%20Thumb">Krark&#39;s Thumb</a> out?</p>

<magic-the-gathering><probability>
How likely is Yusri to get me an omniscience effect, if I have Krark's Thumb out?
AncientSwordRage
# How likely is Yusri to get me an omniscience effect, if I have Krark's Thumb out?

(Asked by: username_0 on 2021-06-05)

The new card [Yusri, Fortune's Flame](https://gatherer.wizards.com/Pages/Card/Details.aspx?name=Yusri%2C%20Fortune%27s%20Flame) has the clause, that if you win 5 flips off it's attack trigger ability, you can cast any card in your hand, *for free!*.

> Whenever Yusri, Fortune’s Flame attacks, choose a number between 1 and 5. Flip that many coins. For each flip you win, draw a card. For each flip you lose, Yursi deals 2 damage to you. **If you won five flips this way, you may cast spells from your hand this turn without paying their mana costs.**

emphasis mine

Normally this gives you a 1/32 chance (1 in 2 to the power of 5), but what happens if you have [Krark's Thumb](https://gatherer.wizards.com/Pages/Card/Details.aspx?name=Krark%27s%20Thumb) out?

**Tags:** magic-the-gathering, probability


---

## 2 answers

### Answer by username_1 on 2021-06-05. Score: 8 | Accepted answer

**The probability to win all 5 coin flips with Krark's Thumb is 0.75^5, or 23.7%, up from 3.1% without Krark's Thumb.**

Normally, you would have a 50% chance to win a single coin flip. Since multiple coin flips are independent of each other, you can just multiply their probabilities, so you get a (0.5)^5 = 0.031 (3.1%) probability to have 5 coin flips go your way.

Each Krark's Thumb essentially halves the probability of losing a coin flip. For one Thumb, It goes from 50% to 25%, so the chance to win goes to 1 - 0.25 = 0.75. The probability to win 5 such coin flips is (0.75)^5 = 0.237, or 23.7%

> **Comments:**
> **username_0**: This is a clever way to do it. I didn't twig the extra thumb halves the failure rate. Much simpler.  

---

### Answer by username_0 on 2021-06-05. Score: 0

For each of the two coins that you flip with [Krak's Thumb](https://gatherer.wizards.com/Pages/Card/Details.aspx?name=Krak%27s%20Thumb) you have an extra chance to win.

This is not the same as flipping double, and keeping the best 5.

Here is the [anydice code](https://anydice.com/program/228f4) I used to calculate this

```
output 5 d [highest 1 of 2d2] -5 named "Flips won"

```

| Dice rolled | Probability to get *at least* that many |
| --- | --- |
| 0 | 100.00% |
| 1 | 99.90% |
| 2 | 98.44% |
| 3 | 89.65% |
| 4 | 63.28% |
| 5 | 23.73% |

So 23.73% of the time you get to cast your cards for free!


---

