@brass-man The two properties that make leyline special amongst other hate pieces are:
- it is probably best hate piece IF you have it in your opening hand.
It is uncounterable, it is free, it is assymetrical, the effect is very potent , it is down on turn 1 no matter if you start on the play or on the draw.
- it is probably one of the worst hate pieces if you draw it later in the game.
If you would draw Leyline, the card is horrible, a lot of decks would have to use extensive resources (crack lotus, use dark ritual etc.) to be able to cast it, or not beeing able to cast it at all and to make matters worse it wont exile anything that is already in your opponents graveyard. However: this downside is so very greatly reduced if you already have a leyline in play from your opening hand and are just drawing your second one. In that case, it most likely doesnt really matter that you have drawn it, since your opponent is already very much desperate to handle your first one which will give you enough time and resrouces to either win, or if you really have no other option cast your second one.
I think these attributes make Leyline very special compared to your peers. In my eyes the whole reason to play Leyline is to have it in your opening hand, if not its just so much worse than other options.
In very extreme terms: Leyline is possibly game winning in your opening hand and absolutely useless outside of it. Logically it should follow that either you want to maximize the possiblity of having it in your opening hand, or just eliminate it all together and go for other options.
I think the 0 or 4 folks are assuming you have to mulligan for Leyline or it's a wasted slot, and the "1-3 is sometimes reasonable" folks are imagining that you don't particularly mulligan for Leyline, and accept that sometimes you start with it and sometimes you don't
"sometimes you start with it, and simetimes you dont" is not a 50/50 thing, it can be modified by playing more or less leylines, and thats the whole point of playing 4 of them. This is like saying "you sometimes win the lottery and sometimes you dont" which is completely ignoring that there is a propability underlying those events.
Also as i explained over and over again in the posts above it is not about always mulliganing to a leyline, it is mulliganing to a keepable hand, while keepable hands are either very broken and fast, or nearly all hands with a leyline in them. Leylines just up the count of keepable hand by a ton. All of this still in the context of playing DPS and following the 'broken or hate' strategy.