FLIP: This card gains 500 ATK and DEF.
If this card is destroyed by battle: The monster that destroyed it loses 500 ATK and DEF.
Rulings
Netrep Rulings
If “Slate Warrior” is flipped as a result of battle, “Slate Warrior's” ATK and DEF bonus will resolve after Damage Calculation.
“Slate Warrior's” "destroyed in battle" effect is not dependent upon “Slate Warrior” being flipped.
Individual Card FAQs
If "Blade Knight" destroys a Flip Effect Monster like "Slate Warrior", even that monster's non-Flip effects are negated. So in this case, "Slate Warrior" does not reduce the ATK and DEF of the "Blade Knight" that destroyed it, because "Blade Knight" negates its effect.
"Gorgon's Eye" cannot negate the effect of "Sangan", "Witch of the Black Forest", or "Sinister Serpent" because they activate in the Graveyard. If a Defense Position "Slate Warrior" is attacked and destroyed, the effect of "Slate Warrior" that lowers ATK and DEF is applied because it activates in the Graveyard.
If "Grave Protector" is on the field, the effect of "Slate Warrior" that reduces the ATK and DEF of the monster that destroys "Slate Warrior" is still applied, even though "Slate Warrior" is shuffled back into the Deck instead of being sent to the Graveyard. The timing of "Slate Warrior's" effect is still at the end of the Damage Step (when monsters are normally sent to the Graveyard after battle).
When a monster's ATK or DEF are changed by its own effect, like "Slate Warrior" or "Berserk Dragon", and "Skill Drain" is activated, that monster's effect is negated and the ATK/DEF are returned to normal. Even if "Skill Drain" is then destroyed, the old adjustment to ATK/DEF does not come back. Any bonuses or penalties are lost when "Skill Drain" effect is applied, and you have to start over from the beginning.
WIND|
Level 4|[ Fiend / Flip / Effect ]
ATK 1900|
DEF 400