I think a tank would be an interesting twist. Maybe have it with a 50% chance to spawn a tank, or an incremental chance. 1st respawn is 1/3 chance, 2nd is 2/3 and 3rd respawn is 100% chance. Does your team run back to defib for -25, or do you risk chancing a tank for that player? Either way there needs to be an incremental penalty for respawning.