In the right shell, he snowballs value every turn
Although each play style is unique for each player, Foundations offers a great starting point for collecting some beautiful cards and practicing the basics of what makes this game great
Its usually best in the 99, but you can run it as your commander too, since its a legendary creature
With both of these effects in play at once, simply dealing one damage to an opponent will drain their life to zero and add that life to your own
The best Ninjas are always those with card advantage on their damage triggers, and while green is already overflowing with this sort of incidental card draw, Avenger could still sneak into some Standard lists
Unless you're the one using it, of course