Say you entangle two particles, and separate them by a long distance. You measure your particle, and know what the other particle will read when it is measured. You now have information on what the other side will see, when they measure the particle.
If you also know some other things about the other side, that it's a deterministic computer, say that will execute a certain action upon reading a "1" and another action upon reading a "0", you now know what the computer at the other side is doing, after you've measured your particle. You know this instantaneously. You know what the other side is doing, you can predict it. And you can devise your own reaction.
Say you know the computer on the other side will launch an attack in one quarter upon reading a zero, and in another quarter upon reading a one. You measure your particle; you now know which quarter the attack will take place, and you can prepare for that.
How is that not information gained at the speed of entanglement, i.e. faster than the speed of light?