Invite them
Normally only the silver flap should have the crimp marks
Personally, Im keeping both my PTCG Live and Pokemon Trading Card Game Online account separate for the purpose of playing in unofficial Pokemon TCG tournaments on the Play Limitless website, coaching, and testing with my friends who only have PTCG Online client
Cards that have high value are generally better to use and should be put into your deck, making other cards that do something, but maybe not as well
The land is legal to play in Legacy, Modern, Commander, Vintage, and Frontier
In the case of my example deck, we can rely on Urborg, Tomb of Yawgmoth and Cabal Coffers combo to ramp us up a bit since were running black