Magic 2015 Seeded Prerelease Booster Strength has no variants:
Explore this pack in Sealed.

Sheets

Sheet common

At rate 1/25 (4.0%)
Blastfire Bolt
Borderland Marauder
Bronze Sable
Clear a Path
Crowd's Favor
Evolving Wilds
Forge Devil
Foundry Street Denizen
Generator Servant
Goblin Roughrider
Hammerhand
Inferno Fist
Krenko's Enforcer
Lava Axe
Lightning Strike
Miner's Bane
Ornithopter
Radiant Fountain
Rummaging Goblin
Scrapyard Mongrel
Thundering Giant
Torch Fiend
Tyrant's Machine
Wall of Fire
Will-Forged Golem

Sheet uncommon

At rate 1/27 (3.7%)
Act on Impulse
Altac Bloodseeker
Belligerent Sliver
Brawler's Plate
Brood Keeper
Circle of Flame
Cone of Flame
Darksteel Citadel
Frenzied Goblin
Gargoyle Sentinel
Heat Ray
Hot Soup
Juggernaut
Meteorite
Might Makes Right
Paragon of Fierce Defiance
Profane Memento
Rogue's Gloves
Sacred Armory
Shrapnel Blast
Staff of the Death Magus
Staff of the Flame Magus
Staff of the Mind Magus
Staff of the Sun Magus
Staff of the Wild Magus
Stoke the Flames
Tormod's Crypt

Sheet rare_mythic

At rate 1/22 (4.55%)
Aggressive Mining
Avarice Amulet
Burning Anger
Chandra, Pyromaster
Crucible of Fire
Goblin Kaboomist
Goblin Rabblemaster
Grindclock
Haunted Plate Mail
Hoarding Dragon
Kurkesh, Onakke Ancient
Obelisk of Urd
Perilous Vault
Phyrexian Revoker
Scuttling Doom Engine
Shield of the Avatar
Siege Dragon
Sliver Hive
Soul of New Phyrexia
Soul of Shandalar
The Chain Veil
Urborg, Tomb of Yawgmoth

Sheet promo

At rate 1/1 (100.0%)
Siege Dragon