Summon: You may sacrifice a unit with
Deadly,
Lifesteal,
Quickdraw, or
Unblockable. Caravan Harpoon gets that unit's Strength and any of those skills the unit had.
Card sounds may differ from in-game as they get updated.
Deadly - Units and spells with Deadly kill any unit they damage, regardless of health. For example, a 1/1 with Deadly can kill a 5/5 attacker.
Lifesteal - Units and spells with Lifesteal give you health when they deal damage, healing you equal to the damage dealt.
Quickdraw - Units with Quickdraw kill blockers before they can deal damage back. Note that Quickdraw only works while attacking, not while blocking.
Summon - Does something when played
Unblockable - Cannot be blocked.