Below the ruins of Shulva waits Elana, a staff wielding queen with some tough tricks up her sleeve. She guards the mural at the entrance to Dragon's Rest, and she defends it well.
First off, check outside the boss room for summon signs--there's no shame in calling others into battle, especially since Elana does it too. She can summon some weak little pigs, skeleton knights, phantoms, or a weakened version of Velstadt, the Royal Aegis. If this happens, make defeating the summon your priority, as the last thing you want to do is get caught between enemies.
As for Elana's attacks, they're quite easy to avoid. At close range, she swipes her staff in a three-hit combo. Block or dodge it, and she'll leave herself open to attack. She also uses several hexes and spells. When she fires dark orbs--either homing or in a sweep--simply keep moving to avoid damage. When she raises her hand above her head, back away to avoid a whirlwind of dark magic. Finally, she'll use the Flame Swathe pyromancy, which takes the form of exploding orbs. When you see these start to form, move out of the blast zone.
With some persistence, Elana won't be too difficult to defeat. Focus on her summons when they appear, and watch for her tells. Bring summons of your own, and she'll go down in no time.
For more help be sure to check out our complete Dark Souls 2 Boss guide.