This spell heightens defense, strength, and agility. Malfurion learned it from Cenarius.[2]
This section contains information from the Warcraft RPG which is considered non-canon.
According to the non-canon RPG,[3] Mark of the Wild is a druidic spell shared by druids, hunters, and elven rangers. By channeling the wild into a willing receptacle a caster can fill an ally with the feral grace and swiftness of the dire beasts of the Emerald Dream. Druids know two related druid-only spells called Greater Mark of the Wild, and Lesser Mark of the Wild.
Trivia
Mark of the Wild is a basic Druid spell in Hearthstone. The flavor text reads: "Not to be confused with Jim of the Wild."
Patch 6.0.2 (2014-10-14): Now also increases Versatility by 3%.
Patch 5.3.0 (2013-05-21): Mana cost reduced to 5%, down from 10%.
Patch 5.2.0 (2013-03-05): Now costs 55% less mana.
Patch 5.0.4 (2012-08-28): No longer increases Stamina and resistances. Mana cost increased from 14% to 22%.
Patch 4.0.1 (2010-10-12): Mark of the Wild no longer increases armor and spirit. Length increased from 30 minutes to 1 hour. Mana cost reduced from 24% to 14% of base mana. If player is in a group or raid and it is cast in a group/raid member, it will affect all members. Group version [Gift of the Wild] has been removed. Associated talent [Improved Mark of the Wild] has been removed. No longer castable on pets.