The Double-Bladed Scimitar can be found in Eberron: Rising from the Last War, page 21.
When you attack a creature with this magic weapon and roll a 20 on the attack roll, the creature must make a DC 15 Wisdom saving throw in addition to suffering the attack's normal effects. On a failed save, the creature also suffers the effects of a polymorph spell. Roll a d20 and consult the following table to determine the form the target creature is transformed into.
| d20 | New Form |
|---|---|
| 1 | Tyrannosaurus Rex |
| 2 | Giant Ape |
| 3 | Elephant |
| 4 | Giant scorpion |
| 5 | Rhinoceros |
| 6 | Polar bear |
| 7 | Giant toad |
| 8 | Giant eagle |
| 9 | Black bear |
| 10 | Crocodile |
| 11 | Wolf |
| 12 | Riding Horse |
| 13 | Ox |
| 14 | Giant frog |
| 15 | Poisonous snake |
| 16 | Hawk |
| 17 | Octopus |
| 18 | Cat |
| 19 | Rat |
| 20 | Rabbit |
A creature is immune to this effect if it is immune to damage of the weapon's type, is a shapechanger, or has legendary actions.
This weapon is cursed, and becoming attuned to it extends the curse to you. Until the curse is broken with a remove curse spell or similar magic, you are unwilling to part with the weapon. Whenever you attack a creature with this weapon and roll a 1 on the attack roll, you suffer the effect of a polymorph spell for 1 hour, rolling on the table to determine your new form.
If you attack with a double-bladed scimitar as part of the Attack action on your turn, you can use a bonus action immediately after to make a melee attack with it. This attack deals 1d4 slashing damage on a hit, instead of 2d4.
This weapon requires two hands to use. This property is relevant only when you attack with the weapon, not when you simply hold it.