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

Flying Melee (Whenever this creature attacks, it gets +1/+1 until end of turn for each opponent you attacked this combat.) Lieutenant — As long as you control your commander, other creatures you control have melee.

Whenever one or more Goblins you control attack, create a 1/1 red Goblin creature token that's tapped and attacking. Whenever another creature you control enters, General Kreat deals 1 damage to each opponent.

The "legend rule" doesn't apply to permanents you control. Each legendary creature you control gets +1/+1. Each nontoken creature you control gets +1/+1 for each other creature you control with the same name as that creature.

Ascend (If you control ten or more permanents, you get the city's blessing for the rest of the game.) Whenever equipped creature attacks, put a +1/+1 counter on each creature you control. If you have the city's blessing, put two +1/+1 counters on each creature you control instead. Equip {3}

Deathtouch, haste When this creature enters, exile up to one other target creature you control until this creature leaves the battlefield. Whenever this creature attacks, for each opponent, create a tapped token that's a copy of the exiled card attacking that opponent. At the beginning of your end step, sacrifice those tokens.

When this enchantment enters, create two 1/1 red Warrior creature tokens. Whenever you attack, each opponent loses life equal to the number of creatures attacking them.

Vigilance Whenever Nadaar enters or attacks, venture into the dungeon. (Enter the first room or advance to the next room.) Other creatures you control get +1/+1 as long as you've completed a dungeon.

Whenever you attack, if it's the first combat phase of the turn, untap all attacking creatures. They gain first strike until end of turn. After this phase, there is an additional combat phase. Choose a Background (You can have a Background as a second commander.)

Whenever this creature attacks, roll a d20. 1—9 | Create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.") 10—19 | Create two Treasure tokens. 20 | Create three Treasure tokens.

Vigilance Whenever this creature enters or attacks, you may return target permanent card with mana value 3 or less from your graveyard to the battlefield.

Flying Whenever Drakuseth attacks, it deals 4 damage to any target and 3 damage to each of up to two other targets.

Vigilance If a permanent entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time. Permanents entering don't cause abilities of permanents your opponents control to trigger.

Myriad The "legend rule" doesn't apply to creature tokens you control. Triggered abilities you control can't cause you to sacrifice or exile creature tokens you control.