Enchantress can be a good mid when you face multiple right-clicking cores and/or heroes that need to be dispelled (Abaddon's aphotic shield, Necro's ghost shroud, etc.). I usually pick her second round or last because I use her as a counterpick, but you can bait burst, break, and anti-regen (Ancient Apparition) heroes by first-round picking her.

Enchantress' strength in mid is in dominating the laning phase and ganking. She's pretty awful at farming overall and doesn't benefit from staying mid past level 7 or so. It's best to have a farming 1 who can take advantage of the space created by an aggressive ganking midlaner (Spectre, Luna, Medusa, etc.). Drow also provides synergy as 1 by boosting Enchantress' attack speed in team fights.

This build is oriented around filling Enchantress' gaps. She's basically immune to long-term damage thanks to Nature's Attendants, so your only resources generally needed in lane are mana and burst HP regen. A void stone is adequate to fulfill most of your mana needs and builds into orchid later. At level 7 the power spike from impetus firing on every shot makes you the hardest hitter in the game at that moment, letting you farm kills in the side lanes. With dragon lance, cloak, and shard you can survive most magic burst combos and hopefully carve enough space for your carry to snowball while you finish your build. Late-game Enchantress with heart and shiva's is one of the tankiest heroes in the game thanks to receiving nearly 600hp/s from wisp regen, and the bloodthorn -> pike combo is enough to kill or nearly kill most six-slotted agility carries.