Maestro sereno (Serene Master)
Maestro sereno 

Texto de reglas (Oracle, inglés)
"Un gran guerrero estudia muchas disciplinas y toma lo mejor de cada una".—Gideon Jura
Legalidad
Aclaraciones de reglas (en inglés)
2013-10-17
If Serene Master blocks multiple creatures, its ability will trigger only once, and it will exchange power with only the target creature. (Note that Serene Master can’t block multiple creatures normally.)
2013-10-17
When Serene Master’s ability resolves, its power becomes equal to the former power of the target creature. At the same time, that creature’s power will become equal to Serene Master’s former power.
2013-10-17
Any power-modifying effects, counters, Auras, or Equipment will apply to the creatures’ new powers. For example, say Serene Master is enchanted with Lightning Talons, which gives it +3/+0, and it blocks a 5/5 creature. After the exchange, Serene Master would be an 8/2 creature (its power became 5, which was then modified by Lightning Talons), and the other creature would be 3/5.
2013-10-17
The exchange is made only if both Serene Master and the target creature are on the battlefield when the ability resolves.