Paladin Elizabeth Taggerdy

Battalion — Whenever Paladin Elizabeth Taggerdy and at least two other creatures attack, draw a card, then you may put a creature card with mana value X or less from your hand onto the battlefield tapped and attacking, where X is Paladin Elizabeth Taggerdy's power.

Adeline, Resplendent Cathar

Vigilance
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.

Krenko, Tin Street Kingpin

Whenever Krenko attacks, put a +1/+1 counter on it, then create a number of 1/1 red Goblin creature tokens equal to Krenko's power.

Anim Pakal, Thousandth Moon

Whenever you attack with one or more non-Gnome creatures, put a +1/+1 counter on Anim Pakal, then create X 1/1 colorless Gnome artifact creature tokens that are tapped and attacking, where X is the number of +1/+1 counters on Anim Pakal.

Mishra, Claimed by Gix

Whenever you attack, each opponent loses X life and you gain X life, where X is the number of attacking creatures. If Mishra, Claimed by Gix and a creature named Phyrexian Dragon Engine are attacking, and you both own and control them, exile them, then meld them into Mishra, Lost to Phyrexia. It enters tapped and attacking.

Isshin, Two Heavens as One

If a creature attacking causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Skyknight Vanguard

Flying
Whenever this creature attacks, create a 1/1 white Soldier creature token that's tapped and attacking.

Fervent Charge

Whenever a creature you control attacks, it gets +2/+2 until end of turn.

Boomer Scrapper

Whenever this creature enters or attacks, you lose 1 life and create a Junk token. (It's an artifact with "{T}, Sacrifice this token: Exile the top card of your library. You may play that card this turn. Activate only as a sorcery.")
Whenever a token you control leaves the battlefield, put a +1/+1 counter on this creature.