Mindless Automaton is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

This creature enters with two +1/+1 counters on it. , Discard a card: Put a +1/+1 counter on this creature. Remove two +1/+1 counters from this creature: Draw a card.

Complete guide

Mindless Automaton is a versatile artifact creature that functions as both a discard outlet and a card-drawing engine. By manipulating +1/+1 counters, this Construct allows you to convert unwanted cards in your hand into growth, or sacrifice its own physical presence to refill your hand.

Counter Management

Mindless Automaton enters the battlefield with two +1/+1 counters, making it a 2/2 by default. It features two activated abilities: one that costs one mana and a discarded card to add a counter, and another that removes two counters to draw a card. Note that neither of these abilities has a 'once per turn' restriction or requires the creature to tap, meaning you can use them as often as you can pay the costs.

Resolution Step-by-Step

When you activate the draw ability, you must remove the two +1/+1 counters as part of the activation cost. This happens immediately and cannot be responded to. Once the cost is paid, the ability goes on the stack. If the removal of these counters reduces the Automaton's toughness to 0 or less (or equal to damage already marked on it), it is put into the graveyard as a state-based action before the ability resolves and before you draw your card.

Strategic Timing

Because Mindless Automaton uses activated abilities, you can react to your opponent's spells. If an opponent targets it with a removal spell, you can respond by removing its counters to draw cards, ensuring you get value from the creature before it leaves the battlefield. Just remember that it must have at least two counters remaining to activate the draw ability.

Interaction examples

Fueling the Engine

If you have Mindless Automaton on the battlefield with two +1/+1 counters and three cards in hand that you don't need, you can pay three mana and discard those cards to put three more counters on it. It is now a 5/5 creature. Later, you can remove four of those counters to draw two new cards.

Construct vs Golem Synergy

Roaming Throne

If you play Roaming Throne and choose 'Construct', it will not affect Mindless Automaton's abilities. This is because Mindless Automaton uses activated abilities (indicated by the colon ':'), whereas Roaming Throne specifically doubles triggered abilities (starting with 'When', 'Whenever', or 'At').

Death and Value

Solemn Simulacrum

Suppose you have both creatures on the battlefield. Your opponent casts a spell to destroy all creatures. In response, you can remove the counters from Mindless Automaton to draw a card. When the spell resolves, both creatures die; Solemn Simulacrum then triggers, allowing you to draw a second card. This sequence ensures you maintain a high hand size despite the board wipe.

Guide written with AI from the official text and rulings. Official English text prevails.