Once again
Monsters do not have priority. The player does.
Now here is how "Exiled Force" can work.
Turn player, player A normal summons "Exiled Force"
Player A uses his priority to activate the effect of "Exiled Force". As a cost for the activation. "Exiled Force" is sent to the graveyard and targets the monster to be destroyed.
For the resolution, the targetted monster is destroyed.
While Player B can chain to the activation of the effect, because "Exiled Force" is already in the graveyard, it can't be "Ring of Destruction"-ed or sent back to the hand or destroyed or anything like that. The only thing you can do is possibly try to activate something that would return the targeted card back to your hand, or offer it as a tribute for the cost of a different effect (like chaining "Enemy Controller", offering the targeted monster, and taking on of the opponent's face-up monsters for the turn).
The only way to prevent it would be "Horn of Heaven" (which will cost you 1 creature on your side of the field anyway) or "Solemn Judgment" (for half your life points) and negate the initial summoning. And no, "Skill Drain" would do anything since "Exiled Force" will be off the field by the time the effect resolves.
- Andrew