Like most Magic: The Gathering cards, the value of Shelob, Child of Ungoliant depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Tales of Middle-earth Promos)
Lord of the Unreal and Timber Protector are excellent inclusions to protect the queen while cards like Hakbal of the Surging Soul and Azami, Lady of Scrolls provide unexpected avenues of card advantage to go with your locus mana
Note that's a cast trigger not an enters trigger, so even if the spell is countered you'll get the effect
Each creature you control assigns combat damage equal to its toughness rather than its power
It also offers more visual contrast than standard stock, ensuring that the graphics printed on each card remain vivid and sharp
In Adventures in the Forgotten Realms, the two things have been fused