As long as you aren't running a Stax deck that is actively limiting your opponents from casting multiple spells per turn with cards like Winter Orb I think you'll get enough value out of Mangara to justify its slot
For each flip you win, create a 2/2 green Sheep creature token named Rabid Sheep
$1.29 Garland, Knight of Cornelia (0486 - Extended Art) Final Fantasy Variants $4.49 Zack Fair (0435 - Extended Art) Final Fantasy Variants $12.99 Terra, Magical Adept (0511 - Extended Art) Final Fantasy Variants $64.99 Cloud, Midgar Mercenary (0375 - Borderless) Final Fantasy Variants $13.99 Absolute Virtue (0476 - Extended Art) Final Fantasy Variants $15.99 Sephiroth, Planet's Heir (0505 - Extended Art) Final Fantasy Variants $5.99 Vincent Valentine (0454 - Extended Art) Final Fantasy Variants $3.99 Choco, Seeker of Paradise (0479 - Extended Art) Final Fantasy Variants $3.99 Jenova, Ancient Calamity (0493 - Extended Art) Final Fantasy Variants $18.99 Kefka, Court Mage (0496 - Extended Art) Final Fantasy Variants $8.99 Clive, Ifrit's Dominant (0458 - Extended Art) Final Fantasy Variants $11.99 Yuna, Hope of Spira (0517 - Extended Art) Final Fantasy Variants 0 results found

Now, you wont pull a card that much from booster packs, but its still worth keeping an eye out for rare cards that could go for a couple hundred bucks