Greninja (5e Creature)
From D&D Wiki
Medium elemental, any alignment
Saving Throws Dex +8
Protean. The greninja can use a bonus action on each of its turns to gain resistance and vulnerability to two different damage types of its choice. When it does so, it loses the previous resistances and vulnerabilities it has.
Torrent. While it has 30 hit points or fewer, the greninja has advantage on attack rolls. In addition, it deals an extra 7 (2d6) damage to any target it hits with an attack.
Multiattack. The Greninja makes three Water Shuriken attacks. If all of them hit, it makes two additional attacks.
Water Shuriken. Ranged Weapon Attack: +8 to hit, reach 40/80 ft., one target. Hit: 9 (1d8 + 5) slashing damage.
Double Team. The greninja moves so fast it appears to separate into two creatures. The greninja moves up to half its speed, creating illusionary duplicates of itself. Any creatures that attempt to attack the greninja has disadvantage against the greninja until the start of the greninja's next turn, when the effect ends.
Greninja are the ninjas of the creature world, striking from the shadows, falling out of trees or off roofs to get the upper hand, and throwing ninja stars made from water. Greninja can compress water into sharp-edged throwing stars. These throwing stars are typically thrown from unseen greninja, never from greninja that you can easily see. Many people who venture into a greninja's home will never see the attack coming... and they'll never be seen again.