Assassinate. During its first turn, the assassin has advantage on attack rolls against any creature that hasn't taken a turn. Any hit the assassin scores against a surprised creature is a critical hit.

Innate Spellcasting. The Yiga Clan are trained in a variety of spells that allow them to easily ambush their targets, ad escape with out notice. The yiga footsoldier's innate spellcasting ability is Intelligence (save DC 12, +5 to hit with spell attacks). The yiga footsoldier can innately cast the following spells, requiring no material components:

At will: Disguise Self, Misty Step

Sneak Attack. Once per turn, the assassin deals an extra 7 (2d6) damage when it hits a target with a weapon attack and has advantage on the attack roll, or when the target is within 5 feet of an ally of the assassin that isn't incapacitated and the assassin doesn't have disadvantage on the attack roll.

Multiattack. The assassin makes two sickle attacks.

Scimitar. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 6 (1d6 + 3) slashig damage.

Duplex Bow. Ranged Weapon Attack: +6 to hit, range 20/60 ft., one target. Hit: 5 (1d4 + 3) piercing damage or 8 (2d4 + 3) piercing damage if the footsoldier chooses to use two pieces of ammunition.