A good site that I've heard of on some other forum for endgame training is https://chess-endgame-trainer.firebaseapp.com/list/4/0
Best way to improve EndGame
There's no need to learn the end game if you can finish your opponents off in the middle game and opening. Just memorize about 50 different openings, and practice tactics. This should get you to at least 2500 rating. The only time the end game is important is at the super gm level where everyone plays for draws.
This is just so wrong. Opening preparation beyond 10-15 moves matters very little under 2000 FIDE, since your opponent will have played something super weird by then. And tactics can only take you so far, even if you are up a bishop in an endgame you need some skill to win, the only way to beat anyone even remotely close to your level otherwise, or draw against a superior player, is to study endgames. And masters typically play to win as much as we do, but actually getting a win against a master is hard, since they are good at holding worse positions. If you are talking about the losing side playing for a draw, does that mean you play for a win when down a queen?!
Thanks Ed