Defender
{1}, Sacrifice Resolute Watchdog: Target creature you control gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)
Resolute Watchdog can be the target of its own ability. The ability won’t resolve since it won’t have a legal target, and no creature will gain indestructible, but this does allow you to sacrifice Resolute Watchdog without another creature to target if you want to.