I placed 3rd in T2 2p at nationals in 2007 using a card with the only duplicate cards outside of Lost Souls being commons, False Peace x5, Burial Shroud x3 and Search (C/D) x5.
You don't have to use lots of copies of cards in decks. It just helps to have copies of the most crucial cards.
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Also, I would just make your first T2 decks out of mostly common cards. You can use necessary duplicates then. Over time, you can replace some of the cards with tin cards or harder to get cards as you gain more copies. You can build cheap defenses that work with only duplicates being commons/uncommons.
Offenses are trickier if you want to run a T2-meta offense, since most of those require multiples of rares/ultras/tin cards. You just have to be creative. You can run a Red Passover Preparations deck, which would cost a few dollars and would make all your common battle winners CBN. You can run a partially green offense cheaply by just using any 4 green heroes and 5 copies of Provisions ($0.25 each).
You can run a really simple brown defense that costs only a couple dollars outside of the staple cards I assume you already have from T1. I made this based on assuming you have one of each brown card at least and the only duplicates are commons/uncommons and Dungeon, which is a $0.25 rare. If you want, I can post a cheap defense for each brigade.
EVIL: 42
Dominants: 5
Burial
Christian Martyr
Destruction of Nehustan
Falling Away
Mayhem
Curses: 4
Unknown Nation x3
Captured Ark
Fortresses: 3
The Darkness
Kingdoms of the World (P)
Gates of Jerusalem
ECs: 15
Haman (promo)
Gomer (TeP)
Esau (Pat)
Unclean Spirit
Foul Spirit x2
Uzzah
Complainers
Abner (k)
King Zedekiah x2
The Jeering Youths
Athaliah
King Jehoram
King Ahaziah
EEs: 15
Shimei's Malicious Curse x3
Gibeonite Trickery x5
Dungeon of Malchiah x4
Crucify Him
Wickedness Abounds x2
Kirk
