Castle Clash IGG new game mode Line of Defence or Line of Defense? Tower Defence|Defense?

Castle Clash new game mode as of Thursday 19th December 2019
Tower defence ez level comes to Castle Clash
To get the new hero
Line of Defence or as some would call it no idea why though Line of Defense
A Tower Defence (aka tower defense) clone with cc heros
Nice f2p way to get the new hero Crystal Wraith within a fortnight?

Defence/Defense?