Yes, the discard will still happen. See this rule :
117.12. Some spells, activated abilities, and triggered abilities read, "[Do something]. If [a player] [does or doesn't], [effect]." or "[A player] may [do something]. If [that player] [does or doesn't], [effect]." The action [do something] is a cost, paid when the spell or ability resolves. The "If [a player] [does or doesn't]" clause checks whether the player chose to pay an optional cost or started to pay a mandatory cost, regardless of what events actually occurred.
[...] Example: Your opponent has cast Gather Specimens, a spell that says "If a creature would enter the battlefield under an opponent's control this turn, it enters the battlefield under your control instead." You control a face-down Dermoplasm, a creature with morph that says "When Dermoplasm is turned face up, you may put a creature card with morph from your hand onto the battlefield face up. If you do, return Dermoplasm to its owner's hand." You turn Dermoplasm face up, and you choose to put a creature card with morph from your hand onto the battlefield. Due to Gather Specimens, it enters the battlefield under your opponent's control instead of yours. However, since you chose to pay the cost, Dermoplasm is still returned to its owner's hand.
Private Mod Note
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I'm a former judge (lapsed), who keeps up to date on rules and policy. Keep in mind that judges' answers aren't necessarily more valid than those of people who aren't judges; what matters is we can quote the rules to back up our answers. When in doubt, ask for such quotes.
Does the "if you do" actually check that a card was actually drawn, or just your choice to attempt that draw?
Specific example: if you have Abundance or Maralen of the Mornsong which prevents/replaces the draw, will his "discard a card" still take effect?
Thank you in advance.
No longer staff here.
Former Rules Advisor
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