Is that a blackthorn glitch or mistranslation?

Hey, been playing the set and found it ... enjoyable, despite the glitches.

Just got a ranked with the Elder Dragon making every augment prismatic and I got pretty lucky. First augment is a random emblem that give stats boost and I got primitive, second was econ, third was the Lux which gave me Blackthorn.

I am playing in french and Blackthorn 6 reads "600 HP, the sacrificed unit isn't killed, instead it gains 150 HP, 10 armor/mr, 10 AD/AP and 20% lifesteal".

So I level up, get 4 primitive and 6 blackthorn, finally put my 3* Primitive Rengar on the blackthorn hex ... and it dies. And I lose from that.

Is this supposed to die and is the french translation just wrong? Do I need to put a blackthorn unit on here for it to not die? Is it just a glitch?