Came as a surprise to us that we were matched with all C rules. Of course I welcome a change of pace and the chance to play with otherwise unused monsters, but I hope SP realises that with these rules relics are ridiculously overpowered.
Pestilence Trap (can be carried by Mersnake): a lvl 30 Pestilence Trap takes off nearly 6000 life at the start of the battle. A lvl 70 Rockilla has 10,550 life. So two pestilence traps at max level will kill anything at the start of the battle that does not carry life runes.
Shield and Armour Relics (can be carried by Rockilla, Light Spirit): Decently ranked Armour and Shield relics can give 20.000+ armour to their wearers (Tenacity Shield even to the entire team) making commons almost untouchable because it (more than) triples their life.
Comeback Essence (can be carried by Treezard): Not as good as armour, but a decently ranked Comeback Essence gives 20.000+ life when the wearer is hit, for 2 turns, still effectively tripling all monster's lives.
Baltasar's Mask (can be carried by Metalsaur and Tyrannoking): Gives a huge damage boost. Tyrannoking's power is 1840 at lvl 70. A decently ranked mask will double his power.
Jakugan Sword (can be carried by Firesaur and Thunder Eagle): at decently ranked level will deal 8000+ damage when triggered. Poof goes the C.
Probably other relics I did not think of as well.