Replace: As of the July 25, 2025 replace to the Complete Guidelines, this interplay has modified. Now Urza’s Saga nonetheless turns into an Enchantment Land — Mountain Saga, for a similar causes mentioned beneath. However this does not trigger you to sacrifice it, as a result of the present textual content of rule 714.4 is:
If the variety of lore counters on a Saga everlasting with a number of chapter skills is bigger than or equal to its remaining chapter quantity, and it isn’t the supply of a chapter capacity that has triggered however not but left the stack, that Saga’s controller sacrifices it. This state-based motion doesn’t use the stack.
(emphasis mine)
Because the Urza’s Saga would not have any chapter skills, rule 714.4 would not apply any extra, and the cardboard stays on the battlefield.
This rule was added alongside the discharge of the Ultimate Fantasy set, which had some Enchantment Creature Sagas within the type of the Summons. Since there are lots of results that may make a creature lose all skills, this interplay turned extra frequent, so the principles had been modified to make it extra intuitive at the price of barely longer guidelines textual content.
(Principally cribbing from this Ask-the-Choose publish on Fb)
Blood Moon causes Urza’s Saga to turn into a Mountain; that is setting a land’s subtype to a fundamental land sort, so is roofed by Complete Rule 305.7:
If an impact units a land’s subtype to a number of of the fundamental land varieties, the land not has its outdated land sort. It loses all skills generated from its guidelines textual content, its outdated land varieties, and any copy results affecting that land, and it beneficial properties the suitable mana capacity for every new fundamental land sort. […] Setting a land’s subtype doesn’t add or take away any card varieties (equivalent to creature) or supertypes (equivalent to fundamental, legendary, and snow) the land could have.
Which means that Urza Saga loses all its chapter skills, however notably does not lose the Enchantment sort and Saga subtype. CR 714.2nd now applies:
A Saga’s remaining chapter quantity is the best worth amongst chapter skills it has. If a Saga one way or the other has no chapter skills, its remaining chapter quantity is 0.
and now the state-based motion from 714.4 applies:
If the variety of lore counters on a Saga everlasting is bigger than or equal to its remaining chapter quantity, and it isn’t the supply of a chapter capacity that has triggered however not but left the stack, that Saga’s controller sacrifices it. This state-based motion doesn’t use the stack.
