Nithgar's Wasting Ward

"Among the protections that every village spellmonger needs in their repertoire is Nithgar's Wasting Ward, or their own master's variation of a weave that will protect stores of grains and other dry crops from spoiling." The tall figure recited to the old man in the robe as they approached the mill and granary. "For the roots and tubers there is another, Kasparas, and for the fruits we use Audra's Lament."
With each addition the old man nodded, then turned his head and asked "Why so many?"
Anticipating this the youth gestured toward the granary up the hill "Each type of crop is attacked by a different foe, and the ward specialized to be very strong against it. You might expect a patron to desire to save coin, and ask for a single weave that will defend against all types of ruin."
A grin could be seen on the old man's face through his thin grey beard as he jingled a small coin purse, eliciting a calm confidence in the youth's voice. "Such protections are possible, but at a cost of their own. Like a lad committing to every contest at the fair, the ward will exhaust itself very quickly if given too many challenges. Such all-purpose weaves need to be renewed far more frequently, and have rarer component requirements as well. A targeted warding renewed annually is the most efficient and reliable."
The young apprentice unlatched the gate and held it open for the master, batting away a pair of curious milking goats determined to inspect their pockets, and resecured the gate behind them as they began the climb up to the granary.
Pausing half way through the climb on a stone slab step worn smooth by generations of millers and their apprentices, the old man took a few breaths and glanced back at the village below. "Do they all need one?" He gestured at the homes and shops spread along the tumbling river's banks.
"Nithgar's Wasting Ward?" The tall apprentice considered, looking at the tight arrangement of rooftops. "I would not refuse the request of a determined patron, but the ward itself is large, requiring some space to lay down the weaves and consuming significant reagents. Shops and stores that hold a large reserve most of the year are best suited. Even with bakeries and breweries we must be careful not to lay the weaves where bread is to be leavened or ales and wines fermented."
"It is a good thing they all have thatched or wooden roofs then." The master said conspiratorially as he turned and began climbing again.
Eyes wide for a moment. "Zarija's Emberquell, another protection that every village spellmonger needs in their repertoire." The apprentice recited.

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Originally written for 2024 Summer Camp challenge answering Technology A PIECE OF TECH THAT PREVENTS DECAY