The Ardenweald Assault is the first series of quest that leads you to Korthia/The Maw. The Winter Queen's sigil is inside of the Heart of the Forest. Sylvanas leads the assault but is thwarted by Tyrande who almost dies. The sigil has been taken. The Primus and Revendreth's sigil remain.
Sylvanas is after the Heart of the Forest and the Mawsworn have taken -all- of the wildseeds.
Tyrande and Sylvanas also fight.