I just noticed a bug with Advanced Search, and a typo.
The Cost field has three operator values: 'Equals', 'Is larger than', and 'Is smaller than'.
'Equals' works as expected.
'Is larger than' and 'Is smaller than' both work counterintuitively. They seem to work as 'equals or greater than' and 'equals or less than' instead of strictly 'greater than' or 'less than.'
An easy example: search the card database with the following values: Rules Text Contains 'buyback', Color Is one of Red, and Cost Is larger than 2.
You will see Blast from the Past, Flowstone Flood, and Reiterate, which all have CMCs larger than 2. But you will also see Fanning the Flames, Haze of Rage, and Shattering Pulse, which all have CMCs of exactly 2.
I see two possible solutions: the first is to change the search logic so that they use the right operators. The second is to change the operator text in the Advanced Search form so that it says 'Is greater than or equal to' and 'Is less than or equal to.' I have a mild preference for the first solution.
Priority seems low: anybody using the cost field to search will likely spot the behavior and correct for it.
Also, there is a typo in the operators for the Cost field. 'Is larger than' appears as 'Is largen than.' The word 'largen' should be 'larger'.
Best,
Scrapulous