Menace (This creature can't be blocked except by two or more creatures.)
Spells you cast that target a creature cost less to cast.
Killian is a Voltron/spellslinger commander that makes your targeted removal, auras, and combat tricks dramatically cheaper, letting you protect and pump him while attacking with lifelink and menace. You curve out cheap interaction, build him into an evasive threat, and grind value with discounted spells until you deal lethal commander damage or out-attrit the table.
Built-in evasion (menace) and lifegain (lifelink) make him a fast, resilient attacker
The discount makes targeted auras, removal, and pump spells absurdly efficient
Two-mana commander recasts cheaply, hard to keep down for good
Cheap interaction means you can answer threats while advancing your own plan
Aura/Voltron strategies are vulnerable to a single removal spell (two-for-one blowouts)
The discount only applies to targeted spells, not creatures or noncreature permanents broadly
Color identity lacks ramp and card advantage compared to other pairs
Removal-heavy or go-wide tables can race or chump-block around him