Phyrexian Totem — ruling 1

A noncreature permanent that turns into a creature can attack, and its {T} abilities can be activated, only if its controller has continuously controlled that permanent since the beginning of their most recent turn. It doesn't matter how long the permanent has been a creature.

Phyrexian Totem — ruling 2

When damage is dealt to Phyrexian Totem, its triggered ability will trigger. A number of permanents equal to the amount of damage dealt will be sacrificed when the ability resolves. It doesn't matter if Phyrexian Totem isn't on the battlefield when the ability resolves, as long as Phyrexian Totem was a creature as it left the battlefield. If one of the permanents sacrificed is Phyrexian Totem itself, the requisite number of other permanents must still be sacrificed.

Phyrexian Totem : règles, fonctionnement et interactions (MTG)

Phyrexian Totem is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

: Add . : This artifact becomes a 5/5 black Phyrexian Horror artifact creature with trample until end of turn. Whenever this permanent is dealt damage, if it's a creature, sacrifice that many permanents.

How it works : Phyrexian Totem

Original English text — Wizards of the Coast / Scryfall

#1August 1, 2008· Wizards of the Coast
A noncreature permanent that turns into a creature can attack, and its abilities can be activated, only if its controller has continuously controlled that permanent since the beginning of their most recent turn. It doesn't matter how long the permanent has been a creature.
No other card is named in this ruling.
#2September 25, 2006· Wizards of the Coast
When damage is dealt to Phyrexian Totem, its triggered ability will trigger. A number of permanents equal to the amount of damage dealt will be sacrificed when the ability resolves. It doesn't matter if Phyrexian Totem isn't on the battlefield when the ability resolves, as long as Phyrexian Totem was a creature as it left the battlefield. If one of the permanents sacrificed is Phyrexian Totem itself, the requisite number of other permanents must still be sacrificed.
No other card is named in this ruling.