Note that this applies only to transforming double-faced cards, not to modal double-faced cards that can normally be played using either face
Sometimes, its also nice to wait until she becomes the target of a spell or ability and then flip her in response to a kill spell targeting a creature
Breath Weapon Choose Your Weapon Concealed Weapon Deathleaper, Terror Weapon Diamond Weapon Dwarven Weaponsmith Efreet Weaponmaster Foam Weapon Kiosk Godo, Bandit Warlord Improvised Weaponry Iron Fist, Living Weapon Legacy Weapon Pact Weapon Renowned Weaponsmith Scavenged Weaponry Seasoned Weaponsmith (playtest) Tawnos's Weaponry The Immortal Weapons Thran Weaponry Toggo, Goblin Weaponsmith Ultima Weapon Viashino Weaponsmith Weapon Rack Weapon Surge Weaponcraft Enthusiast Weaponize the Monsters Weaponized Scrap (playtest) Weapons Manufacturing Weapons Trainer Weapons Vendor World Champion, Celestial Weapon X-23, Deadly Weapon
Even though it cuts Achilless cost in half, Id prefer the buff pre-combat if Im going to invest any mana into it
If it's a green card, add one mana of any color
A humble 2/2 that draws you cards every turn will often outperform a big flashy creature you can barely cast