Gentle Repose [Нетленные останки]

2nd level, Necromancy (ритуал)
Casting time: 1 action
Range: Touch
Components: V, S, M (щепотка соли и по одной медной монетке на каждый глаз трупа, которые должны оставаться там всё время, пока активно заклинание)
Duration: 10 days
Classes: Wizard,Cleric,Paladin
Subclasses: Grave Domain, Circle of Spores

You touch a corpse or other remains. For the duration, the target is protected from decay and can't become undead.

The spell also effectively extends the time limit on raising the target from the dead, since days spent under the influence of this spell don't count against the time limit of spells such as raise dead.

Source: D&D System Reference Document 5.1, © Wizards of the Coast LLC, licensed under CC BY 4.0.