Leyline of Lifeforce isn't bad as a Trinisphere replacement in SB if you've got a metagame full of Threshold, Landstill, and Control. You'd be amazed how easily you can steamroll these decks when they can't counter your dudes.

The only drawbacks are that it takes up sideboard slots that could help in other matchups, and that it will occasionally fuck with your Hellbent. The latter drawback is what keeps me from strongly advocating it in anything but the Bluemost metagames.

Also, be careful about keeping mana-light hands dependent on Chrome Mox with a Leyline, as a lot of decks will suddenly decide that countering that Mox looks like a more appealing idea.