Hello!
Thank you for making a bug report.
I have noticed that you have a Date limitation for your card pool. This looks like the goat format date limitation. The Hero cards, such as necroshade, were released after this date period of 2005-08-17.
A good tip to hosting games is to use the preset buttons when hosting the button to set your settings to the format you are looking for, TCG, OCG, or Goat when you are looking to play in that format.
If you have any other questions, please feel free to ask any questions you have in the Duelist Unite Discord channel #omega_support and the team will be happy to help.
In the mean time, I will be closing this report.
Once again, thank you for your help making Omega be the best it can be.