Panglacial Shinobi

After you activate a library ninjutsu ability, you continue the search effect where you left off. Once the search effect finishes resolving, the active player gets priority with the library ninjutsu ability on the stack. Any abilities that triggered when the ability was activated are put on the stack now.

Activating a library ninjutsu ability while searching your library follows all the normal rules for activating an ability, except for timing (activating this ability always occurs during the resolution of another spell or ability). The ability goes on the stack. You have to pay the ability’s listed costs and any applicable additional costs, which means you can activate mana abilities while you’re activating a library ninjutsu ability even as you’re searching your library.

If you have enough mana and unblocked attackers, you can activate the library ninjutsu abilities of multiple Panglacial Shinobi during a single search effect.

For many playtest cards, you’ll need to make a generous assumption that basic game rules would be updated to allow them to work. The Mystery Booster 2 Playtest Card Notes section (reproduced here in individual Gatherer rulings) provides guidance for fitting these cards into the existing rules structure.

If a creature in combat has first strike or double strike, you can activate the library ninjutsu ability during the first-strike combat damage step. The Ninja will deal combat damage during the regular combat damage step, even if it has first strike.

Although the Ninja is attacking, it was never declared as an attacking creature (for purposes of abilities that trigger whenever a creature attacks, for example).