Crystallized Life

Source
Dropped by Nature elemental themed creatures in Northrend, such as:
 * Thornvine Creeper in Howling Fjord
 * Woodlands Walker or Emerald Lasher in Dragonblight
 * Servant of Freya in Sholazar Basin

Occasionally found by Herbalists in Northrend herbs and when using Mob herbalism on various tree elementals.

Crystallized Life as an ingredient

 * (1 Eternal Life = 10 Crystallized Life and vice versa)

Alchemy

 * Mighty Shadow Protection Potion
 * Transmute: Titanium
 * Elixir of Lightning Speed
 * Elixir of Mighty Defense
 * Flask of Stoneblood

Leatherworking

 * Crusader's Dragonscale Bracers
 * Crusader's Dragonscale Breastplate