Necromancy looks pretty nice according to me, but it may bring madness to games where provinces got trashed through random attacks (swindlers, saboteurs, bridged rogues/knights...)
I like absolution too, but I think we can easily turn a trashing card into an event.
Remodel-ish event
$3
Trash a card from your hand. You may gain a non-victory card costing up to $2 more.
EDIT : well, this is broken in early game. I already imagine the comments : "I'd open twice with this". But hey, you eventually gain $4 cards to start with ($3 cards if playing with shelters), and you filter more quickly. So it ... boosts the early game.
(well, I added the "non-victory" clause otherwise it'd be like Farmland)
Early Altar-ish event
$3
Trash a card from your hand. Gain a card costing up to $4.
EDIT : nevermind, that's the same as above.
Onto funnier (or not) ideas : (most of these are good to me)
Planification
$4
Gain 1 coin token ; +1 VP token.
(too bad it uses two other expansions at once)
Panorama
$3
Set a victory card aside from your hand. Return it to your deck when the game ends. At the end of the game, cards you set aside at least 1 copy of are worth +1 VP.
Bonanza
$4
Once per game : +2 buys, cards cost -$2 until the end of this buy phase, not less than 0. (use some unmarked token)
Treaty
$1
Once per turn : +1 buy. If you buy only victory cards this turn and buy at least one, then draw 1 card after this phase.
Nightwatch (sorry for the name... and the fact I copied a card)
$2
Until the end of your next turn, whenever you gain a card, you may trash it or put it on top of your deck.
At start of your next turn, if you have 4 cards or less, draw until you have 5 cards in hand.
(use same tokens as with Bonanza)
EDIT : removed +1 buy, otherwise it would be almost better than an event that gives you +2 buys for $2 whose I shamefully forgot name
Exploration
$8
You may trash a victory card from your hand. Gain a gold, putting it on top of your deck.
(another idea I brought up from an old contest)