Oath of Chandra — ruling 1

Oath of Chandra’s last ability will trigger even if the planeswalker that entered the battlefield under your control is no longer on the battlefield, no longer under your control, or no longer a planeswalker. This is also true if Oath of Chandra wasn’t on the battlefield when the planeswalker entered.

Oath of Chandra — ruling 2

The last ability triggers only once per turn, even if more than one planeswalker entered the battlefield under your control.

Oath of Chandra — ruling 3

Each of the Oaths is legendary: if you control more than one of any particular Oath, you choose one to remain on the battlefield and the others are put into your graveyard.

Oath of Chandra — ruling 4

The “legend rule” checks the full names of legendary permanents. You can control Oath of Gideon and Oath of Chandra at the same time, for example.

Oath of Chandra — ruling 5

Even if you control a particular Oath, you can cast another of that Oath to take advantage of its enters-the-battlefield ability. It will enter the battlefield, causing its first ability to trigger. You will then choose one to keep, as detailed above, and then its enters-the-battlefield ability will resolve.

Oath of Chandra : règles, fonctionnement et interactions (MTG)

Oath of Chandra 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

When Oath of Chandra enters, it deals 3 damage to target creature an opponent controls. At the beginning of each end step, if a planeswalker entered the battlefield under your control this turn, Oath of Chandra deals 2 damage to each opponent.

How it works : Oath of Chandra

Original English text — Wizards of the Coast / Scryfall

#1January 22, 2016· Wizards of the Coast
Oath of Chandra’s last ability will trigger even if the planeswalker that entered the battlefield under your control is no longer on the battlefield, no longer under your control, or no longer a planeswalker. This is also true if Oath of Chandra wasn’t on the battlefield when the planeswalker entered.
No other card is named in this ruling.
#2January 22, 2016· Wizards of the Coast
The last ability triggers only once per turn, even if more than one planeswalker entered the battlefield under your control.
No other card is named in this ruling.
#3January 22, 2016· Wizards of the Coast
Each of the Oaths is legendary: if you control more than one of any particular Oath, you choose one to remain on the battlefield and the others are put into your graveyard.
No other card is named in this ruling.
#4January 22, 2016· Wizards of the Coast
The “legend rule” checks the full names of legendary permanents. You can control Oath of Gideon and Oath of Chandra at the same time, for example.
No other card is named in this ruling.
#5January 22, 2016· Wizards of the Coast
Even if you control a particular Oath, you can cast another of that Oath to take advantage of its enters-the-battlefield ability. It will enter the battlefield, causing its first ability to trigger. You will then choose one to keep, as detailed above, and then its enters-the-battlefield ability will resolve.
No other card is named in this ruling.