I was trying to think of bonuses that didn’t relate to a death/destruction event like 50% or more of the bonuses out there:
Surprise Mummy, Frenzy Frost Blaster, Stargazer Tower, Cursed Cenotaph, Accursed Tower!
And I came up with one I loved:
If a knight survives for some period of time he’ll clone himself.
So I’d say no bonus strength, no bonus attack.
Just if the knight survives long enough he’ll spawn a new knight.
So really it’s using something similar to the spawn concept via the Gargoyle Nest.