Reproducibility:

Recap:

Description: Dhun versus Aberration, Turn 4 bonus means Dhun heals 4hp. Aberration only plays Sentence, nothing else and no other cards in play provide any healing or additional direct damage effect.
Dhun plays Repulse the Enemy and Gold Medal, there's even a Paladin's Amulet attached.
Dhun suffers 2 dmg from Aberration's physical attack, heals 4hp. But at the end of the turn suffers 22dmg from Sentence

Setup:

Screenshots: