Frenzy
Frenzy is a triggered keyword ability. Transfigure was first introduced in Future Sight.
From the Comprehensive Rules
- 502.66. Frenzy
- 502.66a Frenzy is a triggered ability. "Frenzy N" means "Whenever this creature attacks and isn't blocked, it gets +N/+0 until end of turn."
- 502.66b If a creature has multiple instances of frenzy, each triggers separately.