Cheapest priced copy (Ravnica Allegiance): $1.29 at Card Kingdom, near mint, their price list as of .
Mesmerizing Benthid 
Creature — Octopus · 4/5 · Mythic · Ravnica Allegiance · #43
When this creature enters, create two 0/2 blue Illusion creature tokens with "Whenever this token blocks a creature, that creature doesn't untap during its controller's next untap step."
This creature has hexproof as long as you control an Illusion.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
1 printing · $1.29 to $1.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Ravnica Allegiance | 43 | Mythic | $1.29 | $1.99 |
2 rulings from Wizards of the Coast
- 25 January 2019The triggered ability of the Illusion tokens doesn't tap the attacking creature if it's untapped, most likely because it has vigilance.
- 25 January 2019Mesmerizing Benthid has hexproof as long as you control any Illusion, not just Illusion tokens like the ones created by its first ability.