Legendary Creature — Human Knight
Adeline's power is equal to the number of creatures you control.
Whenever you attack, for each opponent, create a 1/1 white Human creature token that's tapped and attacking that player or a planeswalker they control.
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White legendary that floods the board with soldier tokens on attack.

White Cat legend creating attacking cat tokens when attacking.

Generates and scales attacking tokens each combat in white.

Turns expendable 1/1 tokens into card draw.

Anthem pumping all your created tokens.

Counters pile up as Adeline spawns tokens, growing your team.

Massive anthem and opponent debuff for token armies.

White token-supporting legend with lifegain payoffs.
The ability that defines Adeline's power works in all zones, not just the battlefield. As long as Adeline is on the battlefield (and still a creature), that ability will count Adeline itself.
Attacking with any creatures will cause Adeline's last ability to trigger. Adeline doesn't have to be among them.
Tokens will be created for each of your opponents, not just opponents that you attacked.
You choose whether each token is attacking that opponent or a planeswalker they control as those tokens enter the battlefield.
Although the Human tokens created by the triggered ability are attacking, they were never declared as attacking creatures (for the purposes of abilities that trigger whenever a creature attacks, for example).