Beginner Series
How Combat Works
The combat phase gets one line in most turn-structure overviews, but it's where most beginner mistakes happen. Declaring attackers and blockers, who assigns damage to whom, and how first strike, deathtouch, and trample change the math.
Attacking is optional, one creature at a time — the active player chooses which untapped, non-summoning-sick creatures they control attack, and who or what they attack (a player, or a planeswalker/battle they control). Blocking is optional too, and it belongs to the defending player: for each attacker, they decide whether any of their untapped creatures block it.
An unblocked attacker deals its combat damage straight to whatever it's attacking. A blocked attacker deals its damage to its blocker(s) instead — the defending player takes none of it, unless something (like trample) says otherwise. That last part is where most of the interesting rules live.
MYTH
The bigger creature always wins combat.
FACT
Power and toughness matter, but deathtouch overrides them completely — any nonzero damage from a deathtouch source is treated as lethal. A 1/1 with deathtouch trades with anything. Combat math is about keywords as much as stats.
Combat is section 5 of the Comprehensive Rules, steps 508–510. The keyword abilities that change how damage gets assigned are defined separately, in rule 702.
Comprehensive Rules · Rule 509.1a
"The defending player checks each creature they control to see whether it's affected by any restrictions... Then the defending player declares blockers by choosing, for each of those creatures, whether it blocks. A creature that's attacking can be blocked by more than one creature."
Comprehensive Rules · Rule 510.1c
"A blocked creature that has no creatures blocking it as the combat damage step begins assigns no combat damage, unless it has trample... A blocking creature assigns its combat damage... it can't assign combat damage to a creature that's blocking it unless, when combat damage assignments are complete, each creature that precedes that blocking creature in its order is assigned lethal damage."
Comprehensive Rules · Rule 702.7b
"If at least one attacking or blocking creature has first strike or double strike as the combat damage step begins, the only creatures that assign combat damage in that step are those with first strike or double strike. After that step, instead of proceeding to the end of combat step, the phase gets a second combat damage step..."
Comprehensive Rules · Rule 702.2c
"Any nonzero amount of combat damage assigned to a creature by a source with deathtouch is considered to be lethal damage for the purposes of determining if excess damage is being dealt, unless that source has both deathtouch and infect."
Comprehensive Rules · Rule 702.19b
"The controller of an attacking creature with trample first assigns damage to the creature(s) blocking it. Once all those blocking creatures are assigned lethal damage, the attacking creature's controller assigns the rest of its combat damage to the player or planeswalker it's attacking."
How to take advantage of it
Combat math is the single most common place new players lose value they didn't need to lose.
Order your blockers to minimize losses. When you control the damage assignment order (as the attacker) or choose how many creatures to commit (as the blocker), think about what you can afford to lose — don't throw a creature into a block just because you can.
Respect small deathtouch creatures. A 1/1 with deathtouch is a real threat to your 6/6 — attacking or blocking into it trades your bomb for their one-drop unless you have a way around it (fight it with something expendable first, or just don't attack).
First strike wins damage races. All else equal, a first strike creature beats an equivalent non-first-strike creature in combat every time, because it deals its damage first and the other creature might not survive to deal any back.
Trample punishes chump blocking. If your board is full of big trampling threats, small chump blockers stop being a real answer — factor that in before assuming a token or two will hold the ground.
Should I block this attacker?
1. Does the attacker have deathtouch or lethal power?
→ Yes, and I can't win the trade:
Take the damage instead unless the attacker is about to end the game — losing life is usually cheaper than losing a creature for nothing.
→ No:
Blocking is safer to consider — move to the next question.
2. Do I win or trade favorably if I block?
→ I kill it and survive:
Block. This is the easy case — free removal.
→ We trade evenly:
Consider it, especially if the attacker is a bigger long-term threat than your blocker.
→ I just die for nothing:
Don't block unless you're desperate to save life total, or the attacker has trample and blocking still reduces the damage.