SneakSneak is a keyword that represents a static ability that functions while the spell with sneak is on the stack. “Sneak [cost]” means “Any time you could cast an instant during your declare blockers step, you may cast this spell by paying [cost] and returning an unblocked creature you control to its owner’s hand rather than paying this spell’s mana cost.”
A permanent spell whose sneak cost was paid enters the battlefield tapped and attacking (see rule 506.3a). It will be attacking the same player, planeswalker, or battle as the creature that was returned to its owner’s hand to pay the sneak cost of the spell that became that permanent. (CR 702.190)
Attacking Ninjas you control have
deathtouchDeathtouch is a static ability.
A creature with toughness greater than 0 that’s been dealt damage by a source with deathtouch since the last time state-based actions were checked is destroyed as a state-based action. See rule 704.
Any nonzero amount of combat damage assigned to a creature by a source with deathtouch is considered to be lethal damage for the purposes of determining if excess damage is being dealt.
The deathtouch rules function no matter what zone an object with deathtouch deals damage from.
If an object is no longer in the zone it’s expected to be in as an effect causes it to deal damage, its last known information is used to determine whether it had deathtouch.
Multiple instances of deathtouch on the same object are redundant. (CR 702.2).
Whenever Dark Leo & Shredder deal combat damage to a player,
createTo create one or more tokens with certain characteristics, put the specified number of tokens with the specified characteristics onto the battlefield.
If a replacement effect applies to a token being created, that effect applies before considering any continuous effects that will modify the characteristics of that token. If a replacement effect applies to a token entering the battlefield, that effect applies after considering any continuous effects that will modify the characteristics of that token.
Previously, an effect that created tokens instructed a player to “put [those tokens] onto the battlefield.” Cards that were printed with that text have received errata in the Oracle card reference so they now “create” those tokens. (CR 701.7) a 1/1 black Ninja creature token. Then if you control five or more Ninjas, that player loses half their life, rounded up.