Strictly better describes a card which is, in isolation from other effects, superior to another card in at least one respect, while being worse in zero respects. Cards are commonly found to be strictly better than others by virtue of lower cost, larger effect, instant speed, greater power or toughness, or more versatile or added effects.
"Strictly better" status is not dependent on creature type. More generally, such comparisons between cards are made independent of any particular board state. Therefore, because of the sheer number of possible gameplay circumstances, for any given "strictly better" card, there is typically some imaginable set of circumstances in which it is, in fact, inferior to another card that would otherwise rank below it. This fact implies that a "strictly better" card might be more accurately termed "typically better", and that distinction sometimes confuses newer players. However, "strictly better" is well understood among experienced Magic players, and is the prevailing description of such a relationship between cards.
For example, Lightning Bolt is strictly better than Shock. Both are instants, both cost , and both can target either a creature or a player, but Lightning Bolt deals 3 damage, whereas Shock deals only 2 damage. Although Shock would be preferable to Lightning Bolt if, for example, your opponent controls a Mogg Maniac that you need to kill while you have 3 life, this doesn't preclude Lightning Bolt from being "strictly better," as said circumstances are incredibly niche.
Many pairs of cards are not directly comparable, and thus cannot be termed strictly better or worse. For example, Reprisal and Vanquish the Foul have similar effects, but the latter half of each effect cannot be compared to the other card. Despite Reprisal's lower cost and faster speed, it cannot be termed strictly better than Vanquish the Foul. However, Reprisal is strictly better than Smite the Monstrous, because it has a lower cost and prevents regeneration while being worse in no respect.
The printing of a new strictly better card may make comparable cards obsolete, and this process left unchecked leads to power creep. As rarity has no factor on the definition of strictly better, this occurs relatively commonly with directly comparable cards printed in the same set. Less often, two commons such as Glory Seeker and Knight of Cliffhaven in Rise of the Eldrazi will have this relationship. This phenomenon of strictly better cards within the same set actually goes all the way back to Alpha (e.g., Gray Ogre and Sedge Troll).
More powerful at same cost
The following cards have the same cost, but one has an added ability or greater size.
- Alloy Myr is strictly better than Opaline Unicorn because it has greater power.
- Armored Griffin is strictly better than Abbey Griffin because it has greater toughness.
- Ashcoat Bear is strictly better than Grizzly Bears (and its functional reprints) because it also has flash.
- Hovermyr is strictly better than Omega Myr because it also has flying and vigilance.
- Deviant Glee is strictly better than Unholy Strength as it also can grant trample as an activated ability.
- Giant Crab is strictly better than Homarid Warrior as it doesn't tap to use its ability.
- Lagonna-Band Trailblazer is strictly better than Yoked Ox because it has an added "Heroic" ability.
- Hunted Witness is strictly better than Sanctuary Cat because the token created has lifelink.
- Sejiri Refuge is strictly better than Coastal Tower because it gains life.
- Owlbear is strictly better than Fangren Hunter because it draws a card when it enters.
- Divine Arrow is strictly better than Impeccable Timing because it deals an additional damage.
- Ethereal Armor is strictly better than Lance because it also grants a minimum of +1/+1.
- Dead Weight is strictly better than Weakness because it removes an extra toughness from its target.
- Artificer's Epiphany is strictly better than Catalogue because there is a chance not to discard a card.
More flexibility at same cost
The following cards have the same effect, but one is more restricted in its use.
- Coordinated Assault is strictly better than Kindled Fury, because it can target an additional creature.
- Fury Charm is strictly better than Shatter, because it has two other selectable modes.
- Jungle Shrine is strictly better than Shivan Oasis, because it can provide an additional color of mana.
- Negate is strictly better than Flash Counter, because it can counter additional types of spells.
Same effect but cost less
The following cards have the same effect, but one has a greater cost.
- Control Magic is strictly better than Mind Control.
- Dead Weight is strictly better than Enfeeblement and Debilitating Injury.
- Elvish Archers is strictly better than Hornet Cobra.
- Goblin Tunneler is strictly better than Dwarven Nomad.
- Lightning Bolt is strictly better than Shard Volley.
Instant instead of sorcery
The following are cards that have the same effect and cost but are instants instead of sorceries.
- Boil is strictly better than Boiling Seas.
- Howl from Beyond is strictly better than Bloodcurdling Scream.
- Inner Struggle is strictly better than Wrack with Madness.
Some cards may be strictly better in multiple respects but are only strictly better overall if they have no attributes inferior to the card they are compared with.
- Back to Nature is strictly better than Tranquility because the former costs less and is an instant instead of a sorcery.
- Vulshok Battlegear is strictly better than Warlord's Axe because the former costs less to equip and gives a larger toughness bonus.
- Nova Cleric is strictly better than Squire because the former costs less and has an additional ability.
- Flametongue Kavu is strictly better than Goblin Commando because the latter has less power, costs more, and does less damage when it enters the battlefield.
- Whitesun's Passage is strictly better than Sacred Nectar because the former gains more life and is an instant instead of a sorcery.
- Reprisal is strictly better than Smite the Monstrous because the former prevents regeneration and has a lower mana cost.
- Dragon Mantle is strictly better than Firebreathing because it also draws you a card.
- Strength of the Tajuru is strictly better than Stand Together as they are identical when Strength of the Tajuru is kicked once and X=2, but Strength can also be cast for other configurations.
- Mark Rosewater (March 31, 2003). "This Land is My Land". magicthegathering.com. Wizards of the Coast.
- Mark Rosewater (July 20, 2014). "Does the term "strictly better" care about creature types?". Blogatog. Tumblr.
- Mark Rosewater (September 07, 2017). "Can you please give us a definition of the term "Strictly Better"?". Blogatog. Tumblr.
- Mike Flores (March 03, 2014). "Strictly Superior". magicthegathering.com. Wizards of the Coast.
- Mike Flores (March 10, 2014). "Redundancy". magicthegathering.com. Wizards of the Coast.
- Sam Stoddard (November 4, 2016). "Strictly Better". magicthegathering.com. Wizards of the Coast.