6 * 5 wouldn’t work because there isn’t a number that can replace * to make it a strictly decreasing sequence. You can instead play 6 5 * or * 6 5. These would be different from something concrete like 6 5 4 and 7 6 5, as 6 5 * and * 6 5 wouldn’t get the sequential +1 mult bonus unless there’s enough context to assure that there’s only one possibility for the wild card. So wild cards have pros and cons and it’s important to know when and how to use them.