I always liked the monster surge mechanic. Some time ago I came to think that I'd like to have some more varied effects when a gate surges.
I came up with a simple idea: When a monster surge would occur, instead of resolving it normally, you draw and resolve a card from the Surge Deck.
All effects that would be triggered by a monster surge (e.g. Shudde M'ell's slumber) are still triggered by this modified surge.
Below are some ideas for the cards in the deck: