Equipped creature gets +3/+3 and has first strike.
Equip

Flash
Enchant creature
When Aspect of Manticore enters the battlefield, enchanted creature gains first strike until end of turn.
Enchanted creature gets +2/+0.

First strike
When Attended Knight enters the battlefield, create a 1/1 white Soldier creature token.

As long as Auriok Glaivemaster is equipped, it gets +1/+1 and has first strike.

Flying, first strike
Creatures your opponents control get -1/-0.

First strike
Balan, Wandering Knight has double strike as long as two or more Equipment are attached to it.
: Attach all Equipment you control to Balan.

First strike
Ballynock Cohort gets +1/+1 as long as you control another white creature.

Flying, first strike, lifelink, protection from Demons and from Dragons

Baneslayer Aspirant gets +3/+3 and has flying, first strike, and lifelink as long as you have one or more emblems.

As long as you control another multicolored permanent, Bant Sureblade gets +1/+1 and has first strike.

First strike
Morph (You may cast this card face down as a 2/2 creature for . Turn it face up any time for its morph cost.)

As long as you control a red or white permanent, Battle Brawler gets +1/+0 and has first strike.

First strike

Put a +1/+1 counter on target creature. That creature gains first strike until end of turn. You gain 2 life.

Whenever you cast a spell that's both red and white, Battlegate Mimic has base power and toughness 4/2 until end of turn and gains first strike until end of turn.

Flying
Threshold — As long as seven or more cards are in your graveyard, Battlewise Aven gets +1/+1 and has first strike.

First strike
Belligerent Hatchling enters the battlefield with four -1/-1 counters on it.
Whenever you cast a red spell, remove a -1/-1 counter from Belligerent Hatchling.
Whenever you cast a white spell, remove a -1/-1 counter from Belligerent Hatchling.

Landfall — Whenever a land enters the battlefield under your control, Belligerent Whiptail gains first strike until end of turn.

Flash (You may cast this spell any time you could cast an instant.)
First strike (This creature deals combat damage before creatures without first strike.)

Kicker (You may pay an additional as you cast this spell.)
If Benalish Lancer was kicked, it enters the battlefield with two +1/+1 counters on it and with first strike.