The affected creature doesn’t lose any abilities when it becomes a Serpent.
2020-04-17
wotc
Startling Development overwrites all previous effects that set the affected creatures’ color, creature types, power, and/or toughness to specific values. Other effects that set these characteristics to specific values that start to apply after Startling Development resolves will overwrite that part of the effect.
2020-04-17
wotc
Effects that modify the affected creature’s power or toughness without setting it will apply no matter when they started to take effect. The same is true for counters that change the creature’s power or toughness.
2020-04-17
wotc
Because damage remains marked on a creature until the damage is removed as the turn ends, nonlethal damage dealt to the target creature may become lethal once its base toughness becomes 4.
Format Legality
Standard
Not Legal
Future
Not Legal
Historic
Legal
Timeless
Legal
Gladiator
Legal
Pioneer
Legal
Modern
Legal
Legacy
Legal
Pauper
Legal
Vintage
Legal
Penny
Not Legal
Commander
Legal
Oathbreaker
Legal
Standardbrawl
Not Legal
Brawl
Legal
Alchemy
Not Legal
Paupercommander
Legal
Duel
Legal
Oldschool
Not Legal
Premodern
Not Legal
Predh
Not Legal
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