Mulligans
General Mulligans
All of the lowest cost cards are great to keep as part of the Mulligan with the Aldor Attendant and Truthseeker alongside Cariel Roame for Libram Discounting, though I am still uncertain in what direction would the meta go towards, so it's hard to say on the get go which picks would be the best, however generally the one drops that generate tempo, value and board presence.
Pure Paladin
High Exarch Yrel
With the Pure Libram cards rotating out of the meta, I was wondering whether the newest expansion would still be kind to the Pure Paladin archetype, given that we have Yrel still in play, after her introduction last expansion. The Forge in the Barrens introduces some interesting cards, like Veteran Medic, Kngiht of Anointment and Cariel Roame, which may be able to carry out this archetype, however the biggest flaw of Paladin in general is Card Draw, which the Lightforged Crusader in the previous expansion dealt with, by giving us 5 random paladin cards.
The main idea of this deck is playing minions on curve, while buffing them up with Librams and buffs. Cards like Hammer of the Naaru generate a 6/6 Minion and a weapon 3/3 which is generally a decent stat line and might be quite powerful given the lack of draw of this deck.