Rex, Cyber-Hound + Pili-Pala + Lys Alana Dignitary

Rex, Cyber-Hound

Pili-Pala

Lys Alana Dignitary

How it works

1. Activate Rex using Lys Alana Dignitary's ability by tapping it, adding
2. Activate Rex using Pili-Pala's ability by paying 2 and untapping it, adding one mana of any color.
3. Repeat.