Hmm... well, I wouldn't be expecting such a thing anytime soon, as there is no precedent for such a thing in the game.

Existing precedents and their spell counterparts: (to give you some examples as to what I mean)

We have items that increase our speed...
We have a spell that increases our speed.

We have items that increase our maximum Energy, Mana and Power...
We have spells that increase our maximum Energy, Mana and Power.

We have items that affect the different drop rates of different items (such as the Prospecting Tools which decreases "nothing" chances in favor of "gem" chances)...
We have numerous spells that affect the various drop rates. In fact, this is what the majority of the spells focus on.

We have the Book of Monsters (which unlocks the possibility of monsters dropping 3 items instead of just 2)...
We have a spell that makes monsters always drop 3 items (though this spell kind of sucks since you only get 10 uses of it, and those "items" can be "nothing"s).

We have items that increase the number of Energy we get for each tick...
We have a spell that increases your Energy gains by 4 per tick.


But no precedent exists for altering the appearance rate of things. Even the Quester's Favor spell doesn't affect the appearance of spawning items or chance-encounters.

It's worth noting that we have items which reduce the amount of time needed for each tick, but no spells which reduce the time needed for each tick. So there's a decent chance that we'll see a spell that does that in the future.