You choose which player, planeswalker, or battle the new creature is attacking. It doesn't have to be attacking the same player, planeswalker, or battle that Ilharg is attacking.

If the new creature leaves the battlefield before the end step, most likely because it died in combat, that card remains in its current zone. It won't return to your hand.

If the new creature has an ability that triggers at the beginning of the end step, that ability will trigger and resolve even if the creature is returned to your hand during the end step before that ability resolves.

If one of these Gods leaves the graveyard or exile while its last ability is on the stack, it will remain in its new zone, even if that zone is a graveyard or exile.

If the God's owner has two or fewer cards in their library, the God is put on the bottom of their library as its last ability resolves.

Although the new creature is attacking, it was never declared as an attacking creature (for the purposes of abilities that trigger whenever a creature attacks, for example, such as those of Trusted Pegasus and Makeshift Battalion).

If an effect exiles the God and immediately returns it to the battlefield, its last ability triggers but will have no effect. However, if an effect exiles it and would return it to the battlefield at a later time, the God's ability may return that card to its owner's library first. If it does, the effect that exiled it won't return it later.

In a multiplayer game, if you put another player's God onto the battlefield under your control, it will be exiled as you leave the game. If you were still the controller of that God, you would control its triggered ability but you have left the game; that ability won't resolve and the card remains in exile. Similarly, if you lose the game at the same time that another player's God that you put onto the battlefield is destroyed, it remains in its owner's graveyard.

If one of these Gods dies and it's your commander, you may put it into the command zone before its ability puts it into your library. If you save your commander this way, it won't put it into your library. The same is true if it would be exiled.

If you control another player's God when it dies, you decide whether to put that card into its owner's library.