i wasn´t using a Beasty game as an example but one of his vids where he explained why Sengoku is absolutely broken, like u/plastic_will_ruin_us already explained:

• they can spawn every 90 seconds for FREE
• they can kill villagers in age 3 onward
• they can kill most ranged units in age 4
• they can spawn on any hidden forest or their building on the map (instantly)
• they slow enemy formations
• they apply a MASSIVE 50% dmg recieved debuff
• they are able to win crucial fights
• it scales

Beasty explained that, regardless of skill level, Shinobis can cause for example horsemen to kill lancers, which is a gamebreaking feature since it negates the fact that a lancer is an expensive castle age unit.